Last time I heard, clinching and evading punches are legal in boxing.
It's not the most fun of styles, but it worked. He dictated the fight by effective counter punching and jabbing. And once he sensed trouble looming, he quickly got out of the way.
It's not the most entertaining of styles, but it works. Just like the Spurs. They don't do flashy plays, and they hack the worst FT shooter of the other team, but if it leads to wins (obviously not tonight, but you get the drift), they will do it, and they don't care what others think of their boring, cheating style.
Floyd was masterful tonight. Controlled the fight with his jabs and defense. It wasn't fun, certainly not worth $100, but boxing wise, you couldn't probably ask for a better performance.
FYI, excess holding is actually illegal in boxing. The WBC's rules for a championship contest does indeed recognize "excessive holding the opponent or maintaining a clinch" as 1 of 29 enforceable common fouls that could be cause for penalty or disqualification. It's up to the referee to determine what excess holding is and they tend to let Floyd get away with too much of it.
For instance, Floyd should have been DQ'd in his 2nd fight with Maidana - he held him every time Maidana got within range. It was an awful performance.
The fight Saturday wasn't quite as bad but again Floyd got away with a ton of holding. But Paq has been grossly overrated as a welterweight and Floyd's the better fighter at 147. Manny simply doesn't have the power which is why he hasn't knocked anyone out in 6 years. Once Floyd figured that out (and once Manny was down to one arm) it was all she wrote.
John Ruiz had a similar style - throw a punch or two and then hold. It was effective as long as the referees let it go. But when they wouldn't allow it anymore, Ruiz lost his title to an aging, blown up Middleweight (Roy Jones Jr).