I have so many opinions on this, both pro and anti Mason.
1. Everything he actually said at SCC was true. From the first auditions, we can kind of see who will make it to Judges Houses usually. If you are one of those "segment acts" it's quite high possibility that you won't be past Bootcamp. If they spend a big slot on you, or more importantly the last spot of an audition show, there is a much higher chance you're getting in. Mason was right the fact he has so much less time than others.
2. I don't like him. Despite him saying true things, he said it all wrong. He came across as someone who wants to be like Kanye, and get away with being rude.
3. Another reason I don't like him is because he obviously hated the show before, so it's odd seeing him actually participate in a show he dislikes as he is expressed his dislike on the show before.
4. He DOES deserve a few boos because it's ridiculous he is in the show, BUT on the other side, some may say it's not all his fault. Producers most likely set up his tantrum as by then they may have known that Tom was having doubts about the show (he didn't seem like he wanted to be there during SCC tbh). So the producers expected someone to withdraw, by getting Mason back after his SCC thing, would rile the audience up and get the media to talk about X Factor.
I personally think SCC was set up with Mason in on it. For the first time in years and years, during the auditions, there wasn't that act who kicked off for being rejected (like people like numerous people in the room auditions back a few years ago, Ablisa, etc...), so with no audition meltdowns, they engineered a tantrum/meltdown later on in the series, in this case SCC done by Mason. They didn't want to make it all the way to the live shows without that act who kicks off at the judges.