As always, how can anyone possibly determine the intention? I think the rfl will make an example of us and dock us the two points. I can't honestly say I'd blame them, it's unprofessional at the very least.
If the player entered the field without using the interchange card then IMO Salford as a club have a much stronger case to answer. Players are focusing on the game and want to get on/stay on so you have to give them a little leeway in terms of the process but there is always a member of the dugout staff whose job it is to organise the interchanges. They simply have to get it right. I wonder whether there was one interchange official (the Reserve Ref) or two (often a volunteer from the local society or at SL games could be a reserve TJ). The RR usually notes all the interchanges so there will be some written evidence and maybe video too since it was on Sky.
Some players are less inclined to leave the field when called than others but as professionals they simply have to do it. As an interchange official I've never done a 4 man interchange in one go, but I've done 3 at once quite often and that can be fun.
Largely the system works well and I don't think fans or clubs would want a system that only allowed interchanges at stoppages in play.