I'm not an expert, but if 51% of the existing hashpower doesn't want a change, it sounds less a 51% attack and more like miners voting against something that isn't in their interest. The whole point of blockchains is that the incentives are supposed to be aligned between miners and users. If that isn't the case here, it sounds like a problem.
You should think of miners as bodyguards. They aren't intended to be active participants on the network, they are intended to provide the service of securing the network and serving the interests of the users of the network. If a group of bodyguards at a concert vote democratically and 51% of them decide the singer shouldn't be allowed to go on stage and sing (because of a grudge or whatever), is that a problem? Yes…
I know it’s tempting to discard miners’ concerns, but it would be a great mistake. Miners need incentives, without incentives we’ll start allocating capital and resources somewhere else.
We are not greedy, not crazy, not confrontational: we are just rational.
If someone don’t like us, then could do without us.