He is perfectly sane.
When he found himself facing the flag he understood--and drew back.
A few pirates approach to lead him to the trestle again.

He struggles and pushes them from him.
Ker Karraje and Engineer Serko run up.

They point to the rapidly advancing ship.

They order him to launch his engines.
Thomas Roch refuses.
Captain Spade and the others, mad with rage, menace him--curse him--strike him--try to wrest the phial from him.
Roch throws it on the ground and crushes it under foot.
Then panic seizes upon the crowd of wretches.

The cruiser has passed the zone and they cannot return her fire.