Question about rules/etiquette- stalling

A few weeks ago I played a game (30 min Rapid) 

I got in a winning situation whereby my opponent was down to his King and just a couple of pawns. Both pawns were unable to move, so all he could do was move his King. The situation was completely lost for him unless I blunder and accidentally stalemate him.

We both still had about 15 mins or so left and it was him to play.

Now, I've no problem with him playing on in this situation because at my level (below 700 ELO) accidental stalemate is a distinct possibility and I have done this, to my total embarrassment, in a previous game. So I've no complaints about him refusing to resign.

My issue is that he only had 3-4 legal moves he could make with his King and he took 5 minutes before making a move. OK fine, maybe he was called away from the computer or something happened etc.... and that's why it took him so long to make a move. So I replied and and it was now back to him and this time he didn't make another move and just let his remaining 10 minutes expire and therefore lost via timeout. 

I've no problem with people taking 5, 10, 15 minutes over a move when there are multiple pieces & multiple scenarios for them to ponder but when all you have is 3-4 King moves then surely it is taking the p!$$ to spend so long over it? 

Anyway, Out of curiosity I looked up his game history and filtered his results for "Lost by timeout" and he's got 103 games (out of 294 total loses) that were Lost by timeout.

Some of them were probably genuine losses on time but there's one 30 min game that he lost on timeout but only made 15 moves! 

So basically my questions are:

Is the scenario in the game I described, just "bad etiquette" or are there any rules against it?

Or is it a case of, "It's his time and he can use it any way he likes" Am I being unreasonable here? 

Anyone?

@johnb2023 you are completely right, letting your time run down in a hopelessly lost position is rude and a sign of immaturity as a chess player. Unfortunately, there are many players here that can't cope with losing and this is their way of dealing with it. Report them for stalling and use it as an opportunity to train your empathy and equanimity.

Thanks for the reply.

Since making my OP, I actually looked through a few of his matches that he lost on time, in under 20 moves, and he's basically doing this all the time once the situation has become hopeless.

One game he made no further moves after move 15 with 27 minutes still left on his clock.

This is another reason to report the guy for stalling.

This forum topic does nothing. Staff don't read forums. Report the guy.

I've reported him.

I was just wondering if I was being a bit too harsh or not. I wasn't sure if what he was doing was considered report worthy so to speak.

Yes. It's report worthy.