VA have their own rampies doing the domestic side. Now lets have a look here, there are multiple failings here and a bit of the ownership needs to be placed elsewhere.
The aircraft parking conditions are a major factor here, VGR was pulling into D2 and YID was pushing off E1. Now the first thing to look at here is that E1 and D2 can not be clearly seen from either bay due to the new terminal expansion. There is a light that says that an aircraft is pushing however not arriving.
Second issue, ATC had cleared the driver to push once VGR had parked, now I refer back to the last paragraph and the driver, acting under instruction of the ATCO would have trouble seeing VGR and thus should of had the knowledge to separate the clearances.
Third issue, the JQ pilot SHOULD of advised over the GND that they were holding short of the bay due to what ever the cause was. Thus ATC could of canx the clearance for YID and recleared once VGR proceeded to the full stop position.
Fourth issue, not as relevant however the current works on at D6 has played some part to this with the change in pushback procedures.
It's all well and easy to place sole blame on the driver but understand the facts before you got and solely accuse a single party for all issues.