This blog post doesn't explain what they are actually going to do about this. It's just a (non-legal) complaint about the fact they got a subpoena, which is honestly a pretty normal and uncontroversial thing. It might be bad for Meta to request this info, but if so, the right thing to do is get a lawyer, submit a motion to quash, and then go after Meta for costs through legal process.

What is SimulaVR actually going to do to respond to this? Do they intend to respond? Who's representing them? I can't imagine a lawyer recommended writing this blog post.

The "we can't afford this" argument doesn't hold water. Lawyers are expensive but this is not a complicated thing SimulaVR is being asked to do, and they're likely to get their costs back from the court if they ask.