This is a very good move for telegram. They've became a den for scammers that has been promoting their services and just runaway from their investors. Before it was the users that will just have to ignore those scammers but now there's already an action that they can do.
But let's be honest, if someone randomly decides to report a channel as a scam although it is not, will this be fair?
I believe they apply quantitative metrics on this one, one of them is about 'how many reported the scam channel'. So, it's not like a user reports it as a scam and they got closed down an hour later. However, it's possible that this can get abused too. I personally know at least one user who got the scam tag but later it was removed. Dunno what happens but he probably reported his case to Telegram and explain why he should not be tagged as a scammer.
Probably, there's an appeal for those who got tagged as scam wrongly and became a victim of report abuse.