I think the draw is a valid result. In chess, for instance, there are the three conditions for a draw ... stalemate, thrice-repeated board postions and 50 moves (plus an agreed draw). All are situations where the player who might win should be able to control the play to ensure that the draw does not occur; if they do not, then they do not deserve to win. And so, I think, it should be here. This also ties in with an earlier discussion on the advantage white appears to have in this game and one proposal was touted whereby white could not repeat a move (maybe should be board position?) to generate "perpetual check". Again, I have not found this rule on any other sites, did Linnaeus included something on this?

I think the play by white in this game was quite clever to get to the end position once it was obvious they could not escape (or maybe they were just lucky?!). The more important issue is the game was played under one set of rules and decided by another. This is not the first time rules on this site have been changed mid(post)-game. While you say the King was clearly captured, in terms of the capture rule this is not so and moving into a beavy of defenders is part of the tactics of the game, so why should it change just at the end?