The people behind this slogan were the ones causing the trauma that is now in need of healing. It was often said that the country during Trump's first term was deeply divided. Of course, it was not a neutral statement and was only repeated to get a journalistic point against the president. It was not divided because of MAGA but because of the lies spread about it that many believed.
Saying 'time to heal' after stealing out of hatred a victory for the country is an attempt to lessen the impact and importance of MAGA as if it is some group of disaffected deplorables that need to be brought back in to the status quo of corruption.
It is a tactic where the abuser can stand back after assaulting you and 'innocently' wonder why anyone would not want to heal. The whole idea is to make you feel like you cannot trust what you have seen, that memories are confused and hazy (reshaping the past) and now you continue in your irrationality by refusing the offer to heal.
The objective is to give you a relief for the anger at the injustice you suffered by simply taking the politician at his word that he really does want to heal.
I would not want to ever unite with fraud.