No, the Blocksize wars proved that UASFs SHOULD be respected absent a URSF by miners or the Reorg threat would be very detrimental to miners. (BTW there was already PoW code written if the Segwit UASF failed). The whole reason Miners started running BIP91 was because most of their blocks were being rejected. And the MASF failed at less than the 95% threshold. Roughly 20,000 but there's a bunch of reasons node count is hard to determine.