It's a plot hole. That you can think of explanations for why it isn't used is irrelevant. The hole is in the plot, not in your headcanon.
I.e. there is an element that should affect the plot in a major way, potentially rendering it completely irrelevant, but it isn't even mentioned. They don't have to give a specific reason why it can't act, but it should at least have been noted that it can't.
Just having Turalyon say that the Vindicaar is "currently unavailable" would have been enough.