Is Duoqueue boosting allowed or should I report it to player support?

I know boosting is not allowed, but what if the high elo player makes a new account and uses it to duoqueue with another player in order to boost them.

Asking because I suspect 2 people doing this, having a 90% winrate together on almost 40 games playing Kog'Maw/Support. The support being Gold 1 season 7 and the other was a fresh account. The Gold 1 was actually playing like a gold one, but I had never seen someone playing Kog like that. It was insane. Orbwalking whilde dodging 5 abilities at the same time, and cleansing the one that hit within 0,1 second.

I want to report it to player support, but I don't want to waste their time.

https://www.youtube.com/watch?v=5VWszmkeWww

Decided to go back and check if what HellMaximus1 said was right, and I think he was.

Removed the names from above the champion names in order to not violate the naming and shaming rule. There was a more obvious example, but that had his name in it.