Strange query - tee shot

It depends on wheter or not the sign is deemed to be a movable or immovable obstruction.

I don’t think it matters if it’s a movable or not, relief is only from it impeding a swing.

he should have played it as it lay.

it would be covered under rule 11.

The only remotely similar situation to this I think is if you hit overhead wires, you must tee off again with no penalty. But even that is subject to local rules. Hit a sign, it's play it as it lies, as said above.

It’s amazing how many guys don’t know the simple rules. Not at you OP, but this so called “club golfer” and there are soooooooo many like him, although maybe not quite as blatant as that 🤦‍♂️

if he signs the wrong score on this card then its a DQ

If it is corrected after the hole I assume the hole is scratched in stableford.

On the hole itself I assume he would just have to play it as it lies