The issue with refusing to tolerate intolerance tends to be the difficulty in defining intolerance. There are strong incentives to define intolerance as today's political foes, and weak incentives to resist this urge.
For my own part, I exist in a political context where I know that lots of people want to deny my whole existence. And so long as society is willing to keep them to nothing worse than the occasional unkind word, I'm willing to live with that. I prefer it to the endless mission creep that all too easily comes when the ostracism and purges start.
I know that this didn’t work out in the past and the result were not hurt feelings, the result were millions of murdered people. I know that tolerating intolerance is not solely to blame for that, it probably didn’t even play a major role, but it did play a role. And that‘s why I want to avoid making that deadly mistake in the future.
Yeah, deciding when it is ok is then a hard problem but I’m willing to accept that.
It might be worth recalling that historically, trying to supporess interolant viewpoints often helps make them more popular. Which is to say that intending to avoid repeating a historical mistake may wind up encouraging the exact opposite. Cautious consideration of the possible effects of deliberately adopting intolerance may be worthwhile.
It may also be worth inquiring about what a person means when they refer to their own lives before going on to describe genocide. There's potentially some awkward outcomes there.
For my own part, I exist in a political context where I know that lots of people want to deny my whole existence. And so long as society is willing to keep them to nothing worse than the occasional unkind word, I'm willing to live with that. I prefer it to the endless mission creep that all too easily comes when the ostracism and purges start.