A good reason... because Iku is cute and would be cuter as the uke @heyyy
Honestly, that's also a bad reason. How your look does and should not be the reason for your sexuality or position. If a small cute guy with a "feminine" personality prefers to top, then he's a goddamn seme. No BS such as "I like you more" or sth.
...about that lame ass reason why he should be the seme?
Sorry dude, gotta come better than that. Your reasoning is irrational.