Moral allowances change with times rather dramatically, and a very relative, so I wouldn't rely on them too much. For example, a few centuries ago it was perfectly normal in Europe to marry 13 year old girls.
If it comes to being confronted with the question whether legalizing genocide is tolerable, you claim moral beliefs are so relative that you would not rely on them too much.
If it comes to judging „what a truly tolerant person should do“ you make an absolute normative, hence moral claim.
This strikes me as rather inconsistent and therefore unconvincing.
I am a product of our time and morals of late 20th century. Of course for me, a person born in this age, the idea of genocide looks bad. But if I was born in Russia in 14th century, I'd probably be very fine with the idea a complete and full extermination of every single mongol: men, women, children, all of them. And for a person born in 25th century the idea of genocide might look fine again. Moral is too relative and comes from education and surrounding society, not from some universal rule of what's good and what's bad.
On being 'confronted' with the question about legalizing genocide. Well, if there ARE people with such ideas, it's not like making the ideas illegal will stop such people from having them. So open discussion about it and democratic voting will have just 2 outcomes: nazis will be either reduced to nothing and their political base will dissolve, or they'll get to power and a genocide will happen. However, I believe that a society that will openly vote for genocide is beyond saving, whether you criminalize some ideas or not.
If it comes to judging „what a truly tolerant person should do“ you make an absolute normative, hence moral claim.
This strikes me as rather inconsistent and therefore unconvincing.