Men* shouldn't act like hungry bears. Society at large shouldn't have to assume there's a significant risk that an an unrestrained man will act like a hungry bear. That includes in mixed saunas.

The fear of being a trapped seal is, currently, fairly well-justified. It would be nice to change that.

*: No persons should, but the problems are mostly cis men, like myself.

If that helps your anxieties: having gone to a mixed gym sauna for a long time, I have never ever seen anything remotely inappropriate. People just take the sauna, that is all. If there are any groups coming together, they may chat between themselves, but you'll barely ever hear a stranger even talking to you.

Gym saunas specifically have enough surveillance and multiple controlled chokepoints where perpetrator would be immediately stopped and given straight to the authorities. So, one should be incredibly idiotic to even attempt something like that. In this sense, it is no less safe than any other monitored public facility.

As a personal argument, a lot of predatory behaviors in men stems specifically from something being too limited and restricted. For people coming regularly to the mixed sauna, even those naked ones in some European places, a naked woman is just another naked person. When it becomes mundane, it stops having anything sexual attached to it.