When two wrongs make a right - Maidstone vs Billericay

A fascinating and exciting end to Maidstone's Ryman premier game against Billericay this week.
The Essex team were furious when, in the dying moments and 2-1 down, the referee reversed his decision to give them a penalty when he saw his assistant flagging for an offside moments earlier.

Although I'm only looking at the video and the referee probably had an excellent view, I've got a feeling two mistakes were made.
Firstly, it was incorrect to penalise Billericay for offside. One player was in an offside position when the ball was headed towards the Maidstone goal but he made no contact with it at any stage. Instead, the ball went to an attacker who was clearly not offside (he ran past Maidstone's 4 to get to the ball).
The No. 4 makes an attempt to get the ball but fails and the Billericay striker goes down in a heat after minimal or no contact.It would have been a harsh penalty.
So the right decision was probably reached in the end and the relationahip between referee and assistant worked well in the end, although the team did not appear to be using buzzer flags. It took about 10 seconds before the referee realised the assistant had his flag in the air.
One thing the referee did very well indeed was handling the inevitable anger of Billericay players at the end of the match. On blowing the final whistle. He jogged a good 30 yards away from the players and took up a position to wave players away from him.
With one hand in his card-carrying pocket, he can be seen telling the players to go away or get themselves carded. It worked well with all the players who wanted to give the referee a piece of their miund and probably get themselves sent off for their troubles.
It didn't work as well with the coaching team, who indicated they simply wanted to shake his hand before berating him. I suspect they might have landed in a spot of bother once reports are submitted to the League.