this is a big stretch. Bitcoin miners aren't incentivized to be in consensus. they're incentivized to follow the fork that will make them the most money. Monero miners are only different on n that they might fuck off and do something else if it's more profitable than mining Monero, so you could hypothetically say that you lose network security in that event. it's just a guess though and there's no compelling reason to believe that Monero would lose hash in the event of a contentious fork. lose it to what exactly? why? and no, your umbrel doesn't have any leverage over what miners do. they're looking at where the big money goes and how to remain profitable.

So given that bitcoin is distributed where large institutions hold something like 10% where are these minors going to mine? Where's the valuable bitcoin