There are two kinds of holds. There are the ticky-tack variety that veterans avoid by knowing how to sell it, like a catcher who catches the pitch off the plate and "frames" it to fool the umpire into calling a borderline strike. Then there are the "oh shit I just got pwned" variety where an OL was beat badly and holds out of desperation.
There were a ton of holding calls in this game by both teams, and nearly all of them were of that first variety. One or two of those a game, okay. But 10+, that's just being way too anal about it. The officiating in that game sucked ass overall, and I wasn't a fan of how they called holding either. It's important to remember that many penalties in the NFL have elements of subjectivity and are made in real time, Sweezy was the same guy out there against the Packers that he was against the Broncos, etc. Sometimes you get reasonable officiating, sometimes you don't.
Sweezy was solid in pass pro but will be victimized by fringe holding calls. So will McQuistan. The good news is that fringe holds all but vanish in the playoffs.
Seattle must have led the NFL in OL penalties last season, if not they must have been very close. I think that is the downside to Tom Cable, his lines seem to get flagged a ton, and it's not because they are constantly getting destroyed in pass pro (though Giacomini, Sweezy, McQuistan might have an off day here and there, certainly).