BU alredy endede. No reason for them to fork as they be alt not real BTC like they wanted. Also they can fork at any time, not that they need to be over 51% of Hash
They can fork at any time, but that would make it pointless.
The hard fork will be triggered only when they have substantially over 50% of the hash rate. (Although some miners may be tempted to trigger it as soon as they cross 50%). What the hash rate really tells us is the support they have amongst the miners for increasing block size. This should be a wake up call for Bitcoin Core as well.