Trump has certainly had his share of moments being low class, a brat, a scoundrel, a lout, immature, petulant, insulting and denigrating.
Many of them.
However comparing these two incidents, the handshake snub & tearing up the speech - they aren't really on the same level.
Agreed.
Also, something to consider is that Pelosi apparently broke protocol and and gave Trump a snide introduction, which might make one not want to shake hands with her. Also there is a good case for him not seeing her reach for a handshake as he was turning away at the time. Some say Pelosi stuck her hand out late on purpose, which might be a little tinfoily except for the fact that she was practicing her paper tearing ahead of time. Given that, I wouldn't put a handshake stunt past her.
I still don't like a lot of Trump's tweets and getting into name calling contests, but what Pelosi did during the SOTU (not justthe ripping the speech, but the childish on camera paper shuffling) is just 10x that. There's a big difference between stupid Twitter and live, on camera, official events.