I would argue against that. Why? Drive axles are connected to the transmission. The engine should not vibrate to a noticeable extent if the motor mounts are working correctly. I would argue that the driveshafts would be unable to vibrate if they're inserted into the hubs and transmission correctly. I've seen CV axles done before - there is NO movement in that axle after it's placed into the hub.
I drove around a brand new Chevrolet HHR for months and with the A/C going and the car stopped in drive, the vibration was noticeable (only I had to work to notice it). And that was a brand new car. It's just the way cars are - when you're holding them from doing what they want to do, something has to give. The flexplate can only absorb so much from the motor - the vibration just has to come out somewhere. This is what you feel when you're holding the car back at a light.
And age means nothing? So, rubber as it ages doesn't wear out? News to me and the rest of the world.
The vibration described could be the result of any number of things - worn motor mounts or transmission mounts, idle being too low, idle not being adjusted for the increased load of the A/C, etc. I certainly would not fault aftermarket CV joints as a cause for vibration - there's just no logic to it.