Abbas is pissed off because he is losing support to Hamas. There have been demonstrations and rioting all over the West Bank and his goons have been struggling to crush them. Hamas and the resistance are coming out hugely enhanced from this and the PA is looking increasingly irrelevant. Abbas is hanging on to his UN bid in order to regain some credibility and Israel and the US blocking even observer status on this is undermining him. He needs it to save his scrawny treacherous neck
If, as is looking likely, Israel is hesitating about a ground invasion, then Hamas will have called their bluff, stood firm, demonstrated their ability to attack deep into Israel and to survive. Hamas will be able to present this as a symbolic victory something that will hugely raise their status as the legitimate voice of Palestinian resistance, not only in Gaza but in the West Bank and the Arab world too.