I agree with Grainger that you did the right thing.
As for breaking rules I think it'd only be a problem if you attempted to issue any instructions. but by simply informing people, who were obviously unaware, that a station is closed and then informing them of your position and asking for theirs sound perfectly legal, haven't got CAP413 handy but if there is a rule against it then there really shouldn't be.
As you said, if you'd been at 3000ft and ignored the other guy then things could have taken a turn for the worse.