Looking back at CrimsonKing's decks, the "casual"
scarecrow deck has a $1000 price tag, and so does the "less competitive" deck at $1200. That's maybe an indicator of something.
Blightsteel Colossus is a classic Timmy card, somebody could feel good just getting it out on the field.
Maybe a way to approach a player bringing something unfun to the table is to tell them after the game "That was an awesome deck! What other decks do you have, let's play another game" Validate them, but also encourage them to
explore the space. Many people put their heart and soul into their decks. Decks are personal things. Maybe they spent hours poring searching scryfall for the perfect pieces. Maybe they just dumped their entire budget on a very expensive deck and want to see it in action. Maybe it was the cool decklist they found on here that spoke to them. Commander is very much about community, and if you lose to a deck that wasn't much fun, engage the person again to keep things going. If you leave in a huff feeling bad, they probably just think you are a sore loser or a scrub. It's harder online, but if this is a local store, the onus is on you to build relationships with the other players. (If these are random people dropping in to your space looking for victims, that's one thing)