Not at that levels of output. With large enough machines it's "we're going to spend X to spin everything down, do maintenance checks, spin back up" vs "we're going to pay you X/2 so you take the output and we can keep going". The X may be spent on extra workers, on extra maintenance, on replacement for posts that wear out faster, etc. It's the cost of unusual operation.
And once you're generating there's no great way to just "disconnect" in many cases. If you disconnect the load, the charge still has to go somewhere. Preferably not into nearby equipment. Even the safety switches are non-trivial when dealing with high power - if you break a cable connection, the electric arc will still keep them connected.
