it's not a trump card. nor was it offered as proof that the Seattle DBs didn't play close/dirty/whatever in another SB.
It was a comment to say the Broncos D sucked in the Seattle game and Manning sucked in both SBs, but they won a SB where he really sucked....without any supposed dirty play by the opposing Carolina DBs.
So, to summarize, a solid Broncos D was able to compensate for a disastrous Manning performance vs the Panthers, winning a Lombardi. The D could not compensate for a bad SB performance by Manning vs Seattle.
Put another way, 2 bad SB showings by Manning. The difference was the Broncos Defense, not Seattle's Defense (which as you are keen to point out, did not play in SB 50). This is Manning's MO in SB's. He's, to put it kindly, clutch. In 4 SBs, he has thrown 3 TDs total, and 5 INTS. But yeah, it must have been the Seahawks DBs in that one SB that wrecked Manning's otherwise typically solid SB play over a career.
Does that more the point more clear? I know there are more stats for you to dismiss in place of what you "saw", but I can't describe it in a simpler way.
Own your lazy take and move on.