Re: Silly question...
Sounds like you weren't the 'inside' boat.. If you were clear ahead on the same course and heading you should be able to tack clear anytime you like.. this sounds like if you'd tacked he was likely to nail you before you finished and scooted out of the way.
Sounds like 'tacking too close' to me, esp since you'd be putting yourself on port tack at the same time...
At the same time you should have the expectation of his tacking as soon as possible for the mark, ie I don't think he could continue to sail on just to keep you from making your rounding.
Caveat: It's been a while and I'm probably not current on the rules these days...
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)