The best case scenario here is that Rachel (or one of her associates more likely) takes every single sentence Matt has written here, or anywhere else, tonight, and cross-checks it against every other sentence or fact he's claimed before. Or that his company has claimed. or the foundation has claimed. or ....
Then at the deposition, they will then ask a lot of hard, uncomfortable questions about every single inconsistency, no matter how little. Because that is what they spend many hours preparing to do.
Does similar apply to some of the Automattic employees who have been talking everywhere?
Is there a point where it could switch from "a bunch of people running their mouths" to "a coordinated harassment campaign against WP Engine and its customers"?
Most lawyers in cases like this are not assholes (surprisingly), so they generally won't spend time/energy deposing people who can't produce useful evidence, even if they could.
As a result, you would generally stick to people who have relevant evidence, are capable of legally binding the company (often director or above) or speaking for it (various others), etc.
But - if you need to prove a coordinated campaign, and can't get evidence of it otherwise (emails, chats, etc), sometimes you just got to depose a lot of people.
Usually the path of least resistance is taken, however, and electronic evidence is often sufficient enough these days to not end up having to depose lots of employees.
Judges (magistrate and otherwise) also are pretty careful in ensuring you aren't being malicious (IE just trying to harass employees)
Not a lawyer but have been at some major companies when legal stuff goes down. Most have told us:
"hey, there's a thing going on. Do not talk about it, don't reference it, don't 'correct' people. If anyone asks you for comment, send them to us"
I've been deposed and it sucks. It's exceptionally stressful, even if you're not the target in the situation.