I didn't realise that one could forcibly require a competitor to disclose trade secrets.

Now, INAL of course, but I would think this sort of mechanism would be quite gameable from both sides ( i) a wealthy competitor legally forcing a promising upstart to reveal source ii) a copycat working out some kind of arrangement where the code itself is licensed to them via shell company based overseas.)

As with most legal hacks, the courts figured this one out long ago :).

If someone is trying to dig into their competitor's trade secrets via discovery, the court offers multiple ways to safeguard against that. The defendant can identify information as a trade secret and ask that it be protected in some way - for example, the documents may be restricted to "Attorneys' Eyes Only", so while the plaintiff's attorneys can review the material, the plaintiffs themselves are barred from reviewing it. Or the judge themselves may get involved in an in-camera session.