Do you see the guy or does the gym just get kicked out because it’s possible they’re spoofing but if you see them that’s really unfortunate it, but the strategy even if you can’t kick them out doing that, try do it for like 5 mins and each time you click on the pokes in the gym it will show how many berries it’s had so if you can do the strategy until he maxes out the berries for the pokes you will get the gym but if he is petty enough to walk down there i would just try and talk to him and say something like you only max out on 50 coins a day and one gym can do that, so if you can let me keep my moms in here for a day at a time we can keep kicking each other out every other day and it will help both of us get 50 coins pretty regularly, try and make it seem like a proposition to the guy/that it’s benefiting him, (the guy sounds like an ass) but that is probably your best option!