He got that push because he was was the on who set up the Montreal screwjob.
He was also the one who took the punishment for the curtain call, even though he wasn't responsible at all for it.
Vince owed him.
Doesn't matter - his ring work in 2000 was outstanding. The dude had one of the best single years of any heel, ever, and was the perfect foil to The Rock same way Vince was to Austin. Without HHH, 2000 WWF (minus Austin) starts losing ratings because as good as The Rock is, him fighting Undertaker and Angle every month would've hit them hard.