They've faffed around with the offside law since injury forced me to hang up my whistle so I'm not 100% up to date with everything, but I'm not 100% sure that under the interpretation of the laws that the goalscorer committed an offside offence.
It boils down to whether you judge Jamie Jones initial attempt to catch the ball as a deliberate play of the ball that was poorly executed as opposed to a reflex save that he had no control over where it ended up
if judging that it was a deliberate play of the ball that he messed up then it's no different to that top flight game the other week where one team had a player about 20 yards offside & the opposition defender brought down a punt upfield, played the ball, then got caught in possession by the player who had originally been in an offside position & the attacking team went & scored. As soon as that defender made a deliberate play of the ball, the attacker stopped committing an offside offence
Similarly last night, if you judge that rather than a reflex save Jones tried to catch it, messed it up, then tried to get the ball back then he's deliberately tried to play the ball & the attacker is no longer committing an offside offence & the goal was correctly given
if the initial header had gone down low to his right and he'd parried it in to the path of the attacker then it would have been offside & disallowed. Similarly if Tom Pearce had been on the line & kicked it towards the goalscorer then he wouldn't have been offside
That's how I think the officials interpreted it anyway - although I can see just as strong an argument for the laws to be interpreted for the offside to be given