Hardforks require consensus from the community, not miners. If miners signal for a hardfork, it has no effect on the network even if the signal reaches 100{88c91daedd271a990a10650c05d769cae2765e0603edf30ca95f18704e5748e8}. If they try to violate the protocol rules, Bitcoin nodes will simply ignore their invalid blocks. (This is unlike softforks, where the signals actually activate new features on the network in a backward-compatible manner.)

More recently, BU proponents have been plotting to attack the network before splitting off, by "orphaning" valid blocks that don't signal for BU. The obvious solution to this threat, is for honest miners to falsely "signal" BU, understanding full well that it has no relevance. But as a side effect, BU proponents will no doubt take this as indication of "support" for BU, and try to spin it as such.

So be aware, that just because miners and pools might "signal" BU does NOT mean they support it – they could just as well be trying to avoid being attacked by BU miners. It doesn't mean they're running BU, or will defect when BU splits off, merely hiding from the bad guys.