I have a few thoughts on this. Would such a Policy technically be allowed? I believe so. You are changing the Tactical process, so I don't think it conflicts. However, the Secretary could make a ruling otherwise. I would consider it allowed.
However, I wouldn't recommend it whatsoever. In my experience, a Policy like that wouldn't solve what it's meant to solve - it would only make it worse. The problem seems to be that people are bringing up minor, simple, or not thought-out Tensions to the meeting. Most likely, people are doing that because the meeting is the only way they know how to resolve Tensions, or that's the only place they feel safe doing so.
I've seen proposed solutions like this before, and the end result works in that people don't bring that stuff to meetings anymore, but that's because they simply stopped ever trying to solve any Tensions. They give up on Holacracy and hope. Instead of proposing this Policy, I would recommend creating environments where people can get anything solved more easily. Give them quick access to an expert who can guide them to a solution in the simplest way (which will often not need a meeting), make sure they feel safe bringing stuff up outside meetings, teach them of others ways to solve things other than going to a Tactical meeting, etc.
Hopefully that helps! If you have any other questions, please don't hesitate to reach out!