Do I just need to move this kid to another team more suited to his ability level?

I've just started assisting with the coaching of my son's under-9 team. One particular child has been causing issues with his behaviour which I've tried to address via various methods, with little success.

However, I think the biggest issue is that he is no longer at the same ability as his teammates and is getting frustrated. He is a fantastic goalkeeper but the issues arise in training when we start playing small-sided games, 1v1s etc. He isn't as quick with his feet as the other players and resorts to basically kicking them and going into tackles far too hard. Trying to address this by speaking to him just leads to him shouting and storming off and I think he's becoming a danger to the other kids. On matchdays he's basically allowed to play in goal (this started before I began coaching) as we can't trust him going into tackles.

From what I've learned so far from many excellent FA resources, we shouldn't be restricting his development by 'making' him a permanent goalkeeper at this age so is the best thing to do to move him to one of the other teams at our club at a level more suited to his all-round ability?

Things came to a bit of a head in training this evening when I reminded him that these were his teammates that he was risking injuring and to calm down. He answered that he "didn't care about being part of a team" which to me isn't an acceptable attitude. He also shows this by regularly refusing to keep playing in matches if he's conceded a couple of goals and letting his team down.

Having only been coaching a few weeks it appears a difficult decision to make but I just can't see how we can continue being scared to run sessions in training that are the best for all-around player development, solely because of the potential risks he poses.