Not to current standards, any cable or flex should be 25mm from gas pipe.
So this will be there 2nd mistake...
But Then again you haven't seen where my ring mains and lighting and cooker/electric shower feeds go...
If 25mm is regulations on 3amp flex... I would personally let them off with it... I don't like it near the hot pipes though...
But like u said, if he's done it correct it should be heat resistant which is fine. It doesn't matter where your other elecs go, the wires come from the left, and the wires can go in on the far left of the boiler so don't get why he has run them behind all the pipes and not just behind 1 pipe but whatever your happy with, u did ask if it was correct or not...