Can a 1SG write a policy revoking all passes unless they are requested for a weekend that is already a 3 or 4-day weekend?

NCOs enforce policy, we do not write it. Your 1SG might be the author but your commander has to sign off on it. There by becoming your commanders policy not the 1SG's.

A First Sergeant will occasionally write policy for the commander to review and sign, but ultimately passes are the commander's call.

Most likely what's happening is the 1SG drafted the policy for the commander to sign; that, or the CO directed the 1SG to create said policy. Either way, any such policy would ultimately be coming from the commander, not the 1SG (enforcer of standards, not establisher, yadda yadda).

Additionally, no such policy should even be truly necessary other than to make subordinates aware of the commander's intent. The message he/she is sending pretty clearly comes across as "No passes will be approved," given that any pre-existing 3/4-day weekend wouldn't typically need a pass.

There could be a host of different reasons for doing such a thing (upcoming mission requirements, gross punitive measure to improve discipline, etc.) but ultimately the commander is well within his/her rights to revoke any and all passes should they choose to do so. It's kind of a crummy thing to do, given how powerful of a motivational tool passes can be, but it's a decision that's certainly within the commander's domain.

As far as recourses go, if you truly think it's an unfair policy that's detrimental to soldier welfare and readiness, then phrase it that way to a superior. Start with PSG/1SG and work your way up. There's a small chance that the 1SG doesn't agree with the policy either. If not, then go to the CSM. Remember, your argument should NOT come across as "I want passes because this is unfair", but rather make the point of passes being a useful motivational tool that, when underutilized, can damage morale and unit readiness.

Good luck, SGT, hope it works out.