It is as much a scam as the cards themselves. Artificial scarcity designed to addict our brains to gambling.
The grading feeds on/into the main scam of the cards themselves. The whole cycle requires that we place "value" on their slabs of paper and grading helps make that value more concrete in your brain. The more value you see in the cards the more of them that you want to buy. More cards sold means more grading, so the cycle goes round.
Have fun playing the game, just be aware the whole thing is no different than going to the casino. They just hope the psychological effect of not gambling with money addicts extra people who wouldn't normally gamble with money (i.e. children or those morally opposed to gambling)... and the house always wins.
Because free speech is still a thing. They would need to find evidence that he had/distributed csam content, or had actually molested someone.
Best we can hope for is that they started an investigation and will manage to link something to him, but an adult talking to other adults isn't illegal so they aren't going to arrest him on the spot in the airport.
If they are working on an investigation they won't actually arrest him until they think they have enough concrete evidence to actually win a case, and that is usually weeks/months later.