I guess everyone feared this transition period and the chaos that he could cause. I'm not sure how much irreparable damage he can do to the various institutions, he's done a lot already, but there are some genies that cannot be put back in the bottle, especially on the geopolitical front. His motivation to follow any norms (or laws), or any constraints on his behaviour due to the election is gone. He has nothing to lose now in a lot of ways.
What is amazing, maybe even more so than Trump's behaviour, is that vast swathes of the GOP are totally on board with the notion the election has been stolen. The election has been called, there is no voter fraud, and yet senior GOP figures are calling into question its validity! And now Barr is going down the same road. One party has lost its fudging mind.