It's dumb fam. Read the definition of rival. Luffy does not identify kidd and law as HIS rivals. They may see luffy as their rivals but he does not feel the same way about them period. He doesn't even act that way hence why he hasn't shown himself being super impressed with kidd and he is shown along with zoro even ordering law around sometimes
dude, Luffy did. He did in udon, and he did on the roof. When kid and Luffy claimed they will not dodge before the other one, law just joined. Also Luffy only checked for kids reaction, he didn’t even cared if law is there.
And no, calling others opinion dumb just makes your whole argument unnecessary. How can you expect to get taken serious if you can’t even except other opinions existing?