The linesman’s correct position would be up level with the last defender, so he wouldn’t normally be in a position to call it, if they’ve all pushed up for a long punt. And it’s not something VAR could get involved in.
What has happened if the officials suspect he’s pushing it is the liner will drop back for one. Obviously the ‘keeper unless he’s completely stupid, will notice that and make sure he’s ok for that one. But it would probably put it in his head that they’re on to him and make him more careful from then on.