You can renew Dubai registration annually without the vehicle being present in Dubai. You need to get a local, approved engineer/technician to carry out the inspection on behalf of the RTA (RTA is Dubai's Road & Traffic Authority), then get the test attested and sent back to Dubai. You would then be issues with a gold credit card with registration details - this is how we can travel the world with Dubai plates, without returning home every 12 months.
To have the vehicle registered in Dubai however, he would have to be a Dubai resident, or know someone who could register on his behalf.
Something smells really fishy though as expats aren't allowed to register these vehicles in Dubai, simples.