He's willing to do it because he'll make a deal. On the other hand, the Democrats hate Trump so much, I see it likely that nothing will get done. In a way, that's not a bad thing.
They'll have Trump over a barrel this time. And I can think of few things the left would enjoy more than forcing to Trump to betray his MAGA base, people they loath just as much as they do Trump.
Imagine the "MAGA tears" memes on Twitter as Trump puts his pen to a gun ban.