Unfortunately a lot of younger players can be very rude, immature, and disrespectful. Are all of them? Of course not. But enough are that it gives all younger players a bad name which is unfortunate. If you weren't doing anything wrong then they definitely should not have booted you like that. I've seen a lot of people get booted from fireteams for all sorts of reasons from not having a headset to not being the "right" class. :/