Would it, actually? The EU allows for decompilation in very specific cases and the GPL license means that they must provide their source code because of the way they used the GPL'd code.

If someone in the EU were to request the source code, wait a while to give them a decent amount of time, and then get the source out themselves, I don't know if the court would argue in favour of Voice.ai.

You could argue that distributing the decompiled source would violate some kind of copyright, however the GPL also includes the freedom to redistribute the requested code.

Alternatively, only contributors to the GPL'd software have any legal standing against voice.ai as a random user's freedoms being violated are probably not enforced by the users themselves. The Praat people (a university) and the libgcrypt people (GnuPG) are the ones whose license has been violated so they should be the ones free to sue, possibly with external help (EFF etc.)

I've read about more unexpected turns happening in IP court, who knows what will happen. Morally decompiling would be right, but in a legally speaking I wouldn't risk it.