Why expire a match played almost 90mins

I was playing this match against a meta guy with lot of latest cards and by sheer luck was leading 2-1 into the 90th min.  The connection got disconnected when the result was about to display and after 5-10mins I got a prompt that the match has expired. (I suspect the opponent did something, I know the username but can't report as the expired match result is not shown but that's not the point) 

I can understand expiring a match played for 5-10 mins but after a full match why should it even expire is my question. All it had pending was the result pop up to be shown.