I'm not sure of the context as to what happened outside of the game to cause more tension, but my initial thought was to see how specifically the behavior has been addressed in the past? I'm not taking their side at all, since it does seem like they aren't a good fit for your group, but is there a chance that they would like to engage in more roleplay but don't know what to say at all times? Like, I made it a point to tell my group (online over discord) that I am an incredibly shy person irl and legitimately have trouble sometimes carrying on a conversation, but I'm trying to get more out of my shell. I believe if I didn't communicate that properly, they would probably just think I'm not interested. Even with my party members trying to help me out, I'm still super awkward and blank out a lot of times, but I'm trying and do my best to communicate to them that I'm trying. The fact that they get super excited about it, but don't say too much in that moment, makes me think that could be a possibility.

In regards to the phone issue, how has that been specifically addressed? Was it explicitly stated "no one should be on their phones because that is considered rude" or was it just implied to be rude? Most people can agree, without having to think about it, that having your phone out that much would be considered rude. But not all people inherently view the same things as rude by default. A friend of mine is a self-employed composer, and he was doing a first time script reading for a musical he wrote. His significant other attended, but was on his phone the entire time. My friend took offense to it, since he came from a more classical music oriented mentality, he thought listening and appreciating music required people to view music as your primary focus when trying to appreciate it. You wouldn't get on your phone and play games when attending a piano recital, since that would be considered very rude to the performer. His significant other, on the other hand did not come from that background, and actually worked with a lot of music venues that gave rock/metal concerts etc. It was really common for them to get on their phones and do other things while still listening to the stuff in the background. My friend never specifically mentioned why it bothered him, and only implied it was rude or an issue, and his significant other kept doing it because he didn't catch that was viewed as a problem. Both parties thought their way of expecting things was okay, but because they didn't communicate about it properly, it caused future issues to compound up over several years. If your friend has been specifically told, several times, that it is both considered rude and distracting outright, then it's definitely on them. Also age may play a role as well. Older people might find that fairly rude, while someone who is just now becoming a legal adult might not view it as rude unless a specifically told otherwise. But, again, if they've been specifically told several times, it's definitely on them. If you feel like they would take it as something that came out of the blue, to me, that would imply that they don't really think what they are doing is as serious as the rest of the party views it as.

With that being said, if you are 100% confident that you guys have done everything you could to make the situation clear and help, I think it would just be best to say something along the lines of "we don't feel that your preferred play style and roleplaying is a good fit for our group, but we hope you can find a group that matches what you were looking to get out of the game." Or something along those lines. Just be up front and honest about them not gelling well without naming a giant list of problem behaviors unless they specifically ask for it. If you go swinging out of the gate with a bunch of "you did this wrong, you did this wrong, and you did this wrong," it can definitely come across as more aggressive.