No, I meant that I might be misguided in the case of this particular player, since I don't actually know anything about him or her.
Not allowing game-breaking combinations is common sense. If someone is going to be mopey because I said no to great cleave, whirlwind attack and a bag of rats, fine, be that way. I don't want to game with someone who isn't having fun unless they're ruining everyone else's. It's not "constructive" to circumvent PC abilities by not allowing them to use them. It is constructive to tell the player no, that's too much, I'd rather you didn't play that. Sometimes not allowing something is actually about preserving game balance and not an ugly fascist power play.
I don't fear competent players. I think that when someone takes a dangerous combination and willfully builds on it to make it worse, it's a bad thing. If it were a half-elf Ranger/Rogue with some urban tracking and noncombat feats, I would probably allow it, but it seems they know what they're doing and that is milking a bad thing for all it's worth.