The strongest part of it seems to be that they cite specific activity on Twitter to organise a second attack on the Capitol which is directly linked to these tweets. It seems reasonable to me on the basis that they are basing their actions on actual risk of actual violence occurring as a result of statements. So they have ignored everything up to now because there was not tangible evidence that violence could result. They're now in a position where there is tangible evidence that violence is a realistic outcome from Trump's words, and this has altered their interpretation of his statements generally.