What's your point? Team gains zone entry, establishes extended pressure and then scores.......we want that goal to stand even if they the whistle should have gone for offside? I've heard the argument before regarding how long ago the offside occurred, not sure if that is your point here, but I think that is total BS. If you never gain the zone within the rules, you don't get to keep that extended pressure.....when a team gets trapped in their zone, a good portion of the time it results in 1) icing and still trapped, 2) goal against or 3) penalty....and that all started with an offside, so none of that should have happened. The notion that the offside really has nothing to do with the play anymore if a certain amount of time has gone by is just silly.
I think you started this thread though and I think the difference between calling a goal back for this and not doing it for other things is simply black and white vs. subjective, simple as that.