As a cricket fan, I am not going to make that distinction. Have seen a number of 'nice guys' in cricket who would also break the rules when it suited them. If anything, I would say competitive spirit usually pushes sportspersons to test the limits of the rules and see what they can get away with. So the fault of that lies more with the authorities for not simply handing out time violations as they used to back in the day. I have seen Graf get a time violation at Lipton 93 and Sampras in the Wimbledon 99 final. Both used to play fast. But that's how strict umpires were. It must be the sponsors who forced umpires to bend and crawl for Nadal's sake. I don't blame him for getting away with murder since he was allowed to. But that does not make him arrogant imo, just ruthless and cunning. In other words, you can be 'not nice' and still not be arrogant. Arrogance in sport would have to involve some measure of underestimation of the opponent and I have never seen that from Nadal except during his Wimbledon slump when he was quite pathetic at acknowledging (or not acknowledging) his victorious opponents.
Oh but I absolutely do blame him, there has to be some degree of personal responsibility here. Just because you can get away with breaking the rules (and with such ridiculous consistency) doesn't mean you should, it still reflects poorly on your character. He's not a toddler whose actions can be excused by lax parenting.