But no, they timed their announcement to coincide with interest ramping up in SCO and literally right as the public beta was starting. That's pretty clearly either (or both of) a) trading on SCO's name to get free publicity, and/or b ) trying to derail SCO and make fans lose interest "because after all, the real SC sequel is coming out, so screw the fake one."
A less malicious possibility is that they had already been planning an announcement at some point in 2017 for the 25th anniversary of SC2.
Also, legal conflicts were already brewing before the announcement. By Fred and Paul's account the announcement came only days after an argument over whether the license was still valid - probably not a coincidence. I'm sure Stardock has their own side of how that conversation went, but I doubt they would disagree that there was one. Maybe Fred and Paul thought announcing the game after the argument would be a good way to signal to Stardock "hey, we're serious about that license to our IP having expired" rather than to upstage the beta.
If they hadn't been fighting, we might have found out about Ghosts a couple months later instead. That said, if this was their tactic, it may have been a mistake that helped heat tensions up.
including SC3 which Paul and Fred had no part in building and absolutely no possible claim over. They knew the DCMA would be defeated (and it was) - it was all a tactic.
They licensed their IP for SC3 to be made and sold. If the sales license has expired (which I won't go into the details here, but it is of course one of the central contentions and their argument for it looks at the very least plausible), you would need to get another one from them to sell SC3, so far as I understand these things. Atari and GOG thought so at least.