Ain't nothing corny or "bow down" about this. The biggest "new" rapper asked you, his idols, to be on a track with him. If you think turning him down is some good idea I don't know what to tell you. It ain't about principle either, considering most of these dudes have "sold out" for cash multiple times and performed with a hologram of Ole Dirty.
When Taylor Swift asks her idols to come out for a performance with her, or do a video with her, they do it. You think Fleetwood Mac is hurting for cash? Nah. They do it because they recognize Swift's fans may not know who they are, and therefore doing shyt with her=reaching new fans. I bet you Stevie Nicks thinks Taylor's music is poppy crap, but she still goes out when asked. It has nothing to do with selling out, it's about expanding your audience.
Wu been rapping to the same people for more than a decade. I'm not saying Drake was gonna give them 500k new fans or some shyt, but it's FREE publicity and you can build off that buzz.