Why don't all members of the Air Force have to be fully qualified to be a rifleman in case of hostile events?

I agree, all military personnel should be fimular with the most commonly used weapons at the time of their service.
The Navy is also guilty of not having weapons training. For example the only time I had any weapons training was in boot camp and the rifle we trained with was a 1903 Springfield. I had to qualify at the range with rifle who's barrel was basically shot out. At the time the M14 and M16 were the standard issue for the Army and Marines, but we being taught on worn out 70 year old rifles!!

When I was a kid I competed in rifle competition. My uncle was an officer in AF in Vietnam. When he came home he started winning matches, and I said where did you learn to shoot like that. He said that he learned in Vietnam because often the bases were attacked and they had to practice with m16 on the range regularly.

Thats why we have SECURITY POLICE !!

In Vietnam and Thailand we had Security Police Augmentes. Who were airmen of all kinds of AFSC's who when through a short training, and any time there was a perceived threat to the base they were put out on the perimeter with the regular Security forces. During the TET Offensive the Viet Cong occupied the Barracks area I was in at TSN. The idea that airmen do not need training with Firearms is pure BS.

Run your suggestion up the chain. Who knows, you may get a bite.

The “always a rifleman” concept briefs well, looks great on slides, and even helps motivate at times. But, for some, the expected value of being qualified on a weapons system is much greater than the expected value incurred after calculating the probability that they will ever be in combat. For the Marines and the Army, we do it because for every job, you will likely at some point in your career be assigned to a tactical assignment in which case, your probability of taking fire goes up a lot. The Air Force has a lot of jobs in which the personnel will never see combat. SIGINT linguists in the Air Force for example, you either hang out at a big site in Ft Gordon or Ft Meade or you fly high above the battle somewhere. To me, the Air Force does it right when it comes to calculating these things and actually makes the right decisions more often than the other services when it comes to asset management. And it is because they make the right Benefit/cost assessments and execute based on them rather than use B/C analysis as a “check the block” measure in the acquisition process.

Air Force is not alone! Some navy ratings doesn't require those personnel to familiarize in weaponry, unless they stand watches that requires weapon handling. As a Fleet Marine Force Corpsman, it is a requirement to be knowledgeable in weapon handling and be able to qualify annually. Annual weapons familiarization is must.

I entered the Air Force Mar 55 I was sent to Parks AFB Ca for combat defense school in Jun 55 the course was 5 months and unfortunately we were the last class to get this training some instructors were Army personnel. We were trained in a multitude of weapons mortars recoilless rifle both 30and 50 cal machine gun grenades hand to hand combat law we went into field training etc it is a shame that they did not continue training airman to at least protect themselves .

When we got overrun at Kimpo Air Base by about 100,000 Chinese and NKA in 1950, the only airmen who could use weapons were the 40 Air Police stationed there. The base was evacuated as quickly as possible and those 40 guys held off the enemy for three days. When the Army pushed the enemy back across the 38th, they found those cops hanging in the hanger! From that moment on all airmen were trained in the use of weapons. We have not had a base overrun since that time. I did three tours in the Nam and we were attacked , sometimes daily, and we were never overrun. We still do train them in the use of weapons, but we only make them fire them, normally, before being assigned to a combat area. The difference between us and the other services is that they use their weapons often and because very skilled. Our Security Forces have been sufficient to protect our air bases. The problem is when our airmen leave the base. We have other AFSCs that are very skilled at the use of weapons, normally those who have to operate with the Army or on their own in combat zones, i.e., pararescue, ground air controllers, etc. Another result of the Kimpo incident is that we do not take prisoners unless ordered to do so. Each branch has a different role to perform in battle. Each trains to do just that.

In my 24 years in the Air Force, I qualified on the M-1 Carbine, M-16 and S&W Revolver; Expert in every instance. (In fact, I took easy money from SPs who suggested we have a pot when I qualified with the revolver) Then again, I grew up with firearms and still do well with handguns at age 76.

OTOH, it's true that the vast majority of Air Force personnel have jobs that preclude ever having to use a firearm. That changes if/when they are deployed to combat zones where they can be expected to defend their base. I deployed to Saudi Arabia for Desert Shield and we had weapons available but they were never issued to us while there. I retired before Iraq or Afghanistan but I suspect that many AF personnel - especially in Afghanistan - are armed but would only be used defensively. Infantry combat tactics are not part of AF training.