Should the first amendment be interpreted in a way that makes it to where we cannot say that genocide would be good?

Honestly, no. I think it's better to just have laws against misinformation, and use tactics short of the force of law to ostracize and exclude people who support genocide. Genocide support is kind of untenable if not backed by lies anyway, and the line between the two is ambiguous enough that defining it with actual legislation may cause more problems than it solves. Expel them from universities. Ban them from Xitter. Impeach them if they bumble into a government office. If they say bad enough shit on the clock over a long enough period of time, fire their asses. That would give more consideration to the subjective side of things and lower the stakes in the event of an error.