I think so. It's possible that he is using a very different definition of activation? The only comment I have to work with was this (#1437006)

Scoresby's critique assumes that BIP-110 could fail to activate, but it can't. There's no timeout or "failed" state. Mandatory signaling forces lock-in at max_activation_height, regardless of organic support. The chain-split scenarios described rely on minority hashrate activation, but the 55% threshold prevents this.

So he clearly understands that it activates whether it gets 55% or not. He just seems to believe that it is impossible for it to get any amount of hash rate greater than 0 but less than 55%...

Don't ask me why he chose to set up his game theory matrix this way:

Also in the above tweet, he says "55% is required for lockin, below that nothing activates." I have no clue why he would make this statement and the one on SN which contradicts it.