I tolerate them to the extent that I don't want to murder them, but I don't tolerate what they are saying without challenging it.
I don't think any ideology deserves this amount of tolerance. We should be challenging any idea we think is wrong, whether it be Christianity, socialism, capitalism, fascism, violent video games, hip hop music, whatever.
That's what the alt-right wants when it talks about tolerance, they want people to stop criticising and embarrassing them.
That's what lots of groups want when they talk about tolerance. The alt-right is not special in this regard. Most people in general don't really understand freedom of speech, or why it is beneficial. I hear lots of people talking about how being banned from twitter is a violation of their free speech, or how freedom of speech comes with responsibilities (i.e. only popular speech should be allowed, because unpopular speech is "irresponsible"). And this happens on all sides of all spectra.
And this did not used to be the case, but it seems like it is now, that currently the left is actually the bigger threat to free speech. It's not everyone on the left, and a lot of the fiercest criticism of the anti-free speech left, is coming from the pro-free speech left. This election seems to be somewhat of a repudiation of the anti-free speech left (among many other things), it's just too bad that we also end up with a vindictive idiot child with no respect for intellectual honesty or truth at all as our president.