This sounds like the least arguable edge case possible even if they were interested in chasing it (which they wouldnt be).
Then the vultures will be happy to shake folks down to pay for the licensed version or a law suit. Merit doesn't really matter, they have a claim and fighting it will cost you. They'll just bank on you preferring to pay for the license.
They may not go after the mom and pops, but they'll hit every Fortune 1000 (and probably whether they use MongoDB or not).