Of course Metro was going to get someone who had some exchange with Drake on this album. After that Tweet you can tell he felt some type of way. Can't get Pusha because that's already been done and needed to make an impact after that tweet. What a way to bring it. Plus the roll out to that surprise feature.
Metro really does this producer producer shyt. I still remember when Offset gave his take on how Ric Flair Drip happened. Not just a beatmaker. Dude has a great feel for how to build the hype. That's why he knew the best time to come back to music a few years ago.
Additionally, why would Future be more loyal to Drake over Metro? Metro basically got him his first major W with Karate Chop, got a significant amount of production on DS2, was a major part of WATTBA, etc. If dude heard that Kendrick was going to jump on a track and go at Drake, at worst it's going to be "It is what it is".