What should someone do when they bust tape after a 100% HT/WT and is the only person treated differently than the rest of the company?

There are a number of possibilities as to why others were receiving different treatment. Having said that if you know for fact that all circumstances are the same it is the duty of the first line supervisor to question why so. They should receive a straight and plausible response. If not the Soldier should request open door for the same purpose, seeking answers.

In the end of the day the Soldier should not have busted tape and the NCOIC should not be shocked as they should have known. It is the Soldiers responsibility to maintain standards and the NCOICs to track it. It sounds to me as if we have a failure in personal responsibility and leadership.

I'm in agreement with both SGM Erik Marquez and CSM Darieus ZaGara.

First, I'm surprised by the "Soldiers have 30 days before being flagged" comment. Flagging of Soldiers that fail ABCP is not an optional task for the commander - they are required to initiate the flag when a Soldier changes from a 'favorable' to an 'unfavorable' status. There used to be wiggle room many years ago, but it hasn't been option for the commander for a while - they are required to initiate the flag within three working days of the failure and put them in the program.

I often gave a bit of leeway back in my Company Commander days, but by the time I was a Battalion Commander, I didn't have an option anymore (at least on flags).

Second, flagging actions are like a light switch. You turn them on and you turn them off, especially with the HR systems these days.

Now, putting all that aside for a bit, to CSM Darieus ZaGara's point, while all soldiers should be treated the same (they should all be 'treated right' together or 'treated wrong' together), there could be reasons for 'not giving the Soldier the benefit of the doubt'. I assume there isn't an official policy in the unit's ABCP that Soldiers have 30 days to come into compliance, so it would be one of those "Commander's discretion" things. IF everything is the same, then I agree that they should all be treated the same. However, if the one that was flagged immediately was one of those 'problem children' that has a strike or two against them, then I wouldn't give 'discretion' if I had that opportunity (but, I will reiterate, it's not really an option anymore).

To SGM Erik Marquez's point - the tape test wasn't administered according to Army standards and would need to be redone if challenged. However, I really don't think it's going to change the outcome at all (unless they really fouled up the measurements, subsequent tape measurements would only change a quarter-inch at best) as there would need to be about a 1.5" difference between the readings to make up the 2%. Again, it's POSSIBLE that they really fouled-up the measurements the first time, but as was said, the errors are commonly in favor of the soldier (usually they pull the tape tightly) and not against.

SGT (Join to see) "Also, SM was not taped for a second time, which states in AR 600-9 in B-2e."

Your correct
" If using the circumference methodology outlined in this policy and it is determined that the Soldier’s body circumference does not meet the ABCP standards, a confirmation will be completed. The above process will be completed by a
different team than the completed initial set of measurement. This must occur before any actions are taken by the commander."

And regs are regs for a reason, the circumference methodology is difficult to administer properly, and its not uncommon to have it done incorrectly. (commonly in favor of the SM, not against. )

So sure, the SM can point out the error in the procedure and ask for a second testing...likely that will result in two new teams being tasked immediately, the SM escorted to residence to change into the required uniform, escorted back to the unit testing location where they will have the test performed again under a circumference methodology trained senior supervisors observation.
If the SM passes, the flag should be voided for having been erroneously emplaced
Id also expect the CDR to critically observe the SM each time they are in uniform and if that CDR determines in their opinion the SM does not does not present a Soldierly appearance that CDR has authority to direct a body fat assessment

" d. Commanders have the authority to direct a body fat assessment on any Soldier that they determine does not present a Soldierly appearance to ensure Soldier meets the screening table weight for his or her measured height. "

A better plan might be, use the opportunity to better ones self with GREAT motivation. Use the resources that are not just available, but by Reg MUST be provided