My immediate thoughts were:
1) He's only doing this because Drake did it.
2) She didn't know you, it's weird. (I thought this about the Drake one too.)
3) Why? Aaliyah had an interesting icy quality to her voice but most Chris Brown fans won't have a clue who she is; and I imagine most Aaliyah fans will be outraged at the idea but ultimately lap it up because it's unheard material.
Sigh. I don't even get offended by his bull**** anymore, I've come to accept that he's here for a while but hopefully his career will die out after another couple of years. The guy's not even that talented, I swear half the people who buy his music are doing it purely to troll.