I followed this up with Allianz Roadside Assistance today.
Can confirm the 3500kg limit relates to the vehicle GVM even though GVM is not used in the definition.
Also confirm that the weight limit relates to recovery weight as
@AnD3rew suggested above.
Allianz CS advise that "because the Grenadier GVM is less than 3 tonnes it's good to go". Yep, that's what they said. Naturally I persisted to ensure they understood the question and the Australian spec @ 3550kg rated GVM. After a bit of to and fro I was put on hold while a Team Leader was consulted. Team Leader confirmed: "Because the Grenadier GVM is less than 3 tonnes..." Thank you. Have a nice day.
They had the wrong registration number listed for my vehicle and couldn't find my roadside policy using the VIN - even though the correct VIN was on the letter they sent me in the post. Those minor details aside, I'm sure it's a good service.