[bluejak]

How other people play the sequence is hardly relevant. In fact some people play it as signoff and some as game forcing. I ought to know: I play it both ways with different partners. Whether one method is better than the other is irrelevant for ruling purposes, as is how this pair plays it.

All that matters is that South thought is was not forcing, he had UI from partner, playing it as non-forcing enough people here pass that pass is clearly an LA. So the only question of any interest, surely, is whether the BIT suggests bidding on over passing.

I think yes and rule it back.

[Poky]

Opponents probalbly play 18-19 2NT rebid but they upgraded a beautiful 17 count (as anyone should do).
The first thing director should do is to check what's 1m-pass-2M in their system.
If they have an agreement that's a weak-2 then it is clear 3♥ now should be treated as forcing.
But obviously, opener's comment makes clear this is hardly their agreement, so, an adjustment to 3♥ could be in order as a slow 3♥ cannot suggest a weak hand.