I fully support the efforts to impeach President Trump, if for no other reason than to prevent him from being able to run again. I also support Twitter's right to kick him off their platform.
That said; it seems a stretch to me to permanently delete his account based on the two tweets they cite. They're about to break their necks trying to find problems in those two tweets when they have a smorgasbord of inflammatory tweets over the years to pick from. Saying he won't attend the inauguration was the final straw? It really seems disingenuous on their part.
I would respect them far more if they had said, "You know what? Our decision to reinstate his account after twelve hours was a mistake. Donald Trump is clearly harmful to our republic and we will no longer give him a voice on our platform. His account is therefore permanently suspended."