I had the same thing happen and I was actually moving around when it happened. Fireteam friends witnessed it. I think if you do not kill any opponents or get killed by opponents for a period of time, it boots you whether you are moving or not, which I consider unfair.

I know this doesn’t help but you technically were inactive for more than 2mins, No it shouldn’t happen in a situation like this, but I’ve never seen a round last that long after only 1 team mate is left. The inactivity was set to stop people just logging in letting other play so as to farm rewards. Bungie had to set a time limit I know that I will always flick between remaining players or change the view perspective. Only time I experienced a inactivity disconnect was when I had to answer a phone call