[greenshackle2]

It's unclear from the article whether:

1) RoboVM had to use the GPL license because they used other people's GPL code - which they presumably pulled out / rewrote themselves in their new closed-source version

or

2) the author mistakenly believes that RoboVM is bound to the terms of the GPL license, or forced to offer new GPL licenses, on code they own 100%, just because they have offered GPL licenses to other people in the past

[invalidname]

3) They released a binary and included the GPL license as part of the binary release licenses thus committing to the GPL in that release while not making the code available.

[greenshackle2]

If they owned 100% of the copyright, then it still wouldn't matter. The GPL gives additional permissions, along with some restrictions / obligations, to Licensees. As copyright holder you are not a Licensee.

You do not need to grant yourself a license to distribute your own works. You always had that right.

Besides, who would sue you? The only person who has standing is the copyright holder. You're gonna sue yourself because you failed to honor the terms of a license, which was granted from yourself to yourself?

If they didn't own 100%, then see 1).

[invalidname]

Feel free to check their old Google group. It's still around somewhere.