I dont think he awarded the goal immediately either. I think if you watch it back he immediately says to Brentford players "it's getting checked" almost immediately. Which I've no problem with, if he had doubts that's absolutely fine, doesnt really matter if he awards a fk or awards the goal when he knows for sure it needs checking.
For him not to be told to go and check it for himself, is baffling. VAR officials cannot have been sure about giving that as handball. They just couldn't have. At least if the referee goes and looks, and then rules it out at least then you've got two officials both with the same judgement.
If me and you see an incident, we may both have different opinions on it. So if the ref goes over and disagree's with VAR, then they keep it as on field and hte referee effectively takes control. Perhaps would be brave but when there is an incident like that and they can't be sure, they have to let it go. If the referee goes over to the monitor and says yes, i think it hits his hand. At least then you've got some sort of safety in numbers and your likelihood of being right at least goes up a little.
For all we know the ref may have seen it at half time, or full time and gone, that didn't hit his hand. VAR got that wrong, but he's taken it out of his hands by not being told to go and check the monitor.