The other day I was fleeing from a pursuing gunboat, both of us at cruise speed, he was around 2k away from me. I engine killed, spun around (while maintaining cruise speed due to the ill), and launched a few disruptors at him to kill his cruise so I could get away.
To me that seems like a tactic and good use of ship capabilities. He could have fired a CD at me (if i was in range, so was he) to stop my drifting, but by the time my disruptor hit he wasnt able to get back in range.
That's illegal. Since you were cruising first (you said you were fleeing, right?) that counts as re-engagement, since the pursuer has to open fire first when both have engaged cruise.