Why did Floyd Mayweather Jr come back to fight JMM, instead of Luis Collazo?

I ask this question because Floyd made Juan Manuel Marquez come up 2 weight cles to fight him. At the time JMM only had 2 fights at lightweight (Diaz, Joel). I know JMM was #2 P4P and we all know Floyd wanted to show up Manny because Manny struggled with JMM. BUT I would have rather love to see him fight Luis Collazo as an easy come back fight because I would of giving him more respect for beating an actual WW and not a lightweight. I'm just saying that there was other fighters at WW that wouldn't be a threat to Floyd and still have his win look good instead he fights a much smaller man...I just don't get Floyd and will never get him. I miss the golden age of boxing when no one ducked each other and fighters fought other fighters of the same size.