I might cut the other guy some slack. While I--of course--have no idea what actually happened in your game, isn't it possible that this was the 3rd game today where that guy had been (from his perspective) slow-played by other players? And he could have said something in chat, but instead kept quiet (some would say: polite) and waited for the full time-period and only then did DQ you. That seems pretty possible to me. In other words, I would not impute bad motives to someone I do not know, unless some other factor(s) suggests this.
I'll point out that 4-5 minutes is an INCREDIBLY long time to think about a single move. I could possibly see taking that long if you are playing a game with several cards that are new to you...but then we'd be taking a long time in the very beginning of the game (and presumably we would have sent a text like "Sorry--there are new cards for me. I'll need a few minutes to read their text" to let the other person know why there's such a long delay.).
I know that just because I can't think of a kingdom where I would take more than a minute or two to make a move at the end of the game, that does not mean that no such kingdom exists. But we can use your experience as a teachable moment...if we find ourselves taking more than a minute or two; we really should take 15 seconds out of our turn to send off a quick chat message: "Sorry about the delay, making a hard decision; will be just another minute."
Just a suggestion. :-)