I’m not offended and I don’t have a stake in 3M! My installer does both (Xpel & 3M) and kicked me over to 3M for a reason. I’m not going to bash any product because paint protection film is great in my opinion no matter who you go with!
3M is easier to work with and cheaper, so if he quoted you the same $ for either film, that's why he may have pushed 3M