From my understanding, low chance.
I might be wrong - please someone with real knowledge confirm/refute this -
But they just can't.
OP_RETURN is a clean way to satisfy +/- everyone.
Without it, you can use multi-sign (even if I don't concretely understand it), what the dev just did.
And even if that fail, you can always link a message to every transaction.

So at worst, they could make it more expensive, but not stop it.