Ya reckon? :-/
Yes, I think I'd stand by that comment, by and large. Of course the TT course is more dangerous for a bike rider, and as Albs says, you'd much rather be hitting one of those walls with some car metal than your own helmeted head, but its the lack of room on the road, the narrowness of the racing line which is more evident in a car - it just looks scarier!

Certainly the width is a factor as you say, the side cars struggle to pass each other on the course. But given a car will brake and corner more effectively than a bike, due to physics and body position in/on the vehicle, I'm thinking the bike has to work harder ....? The battering is far more pronounced and the speeds higher with less conferring and braking potential available for the biker to keep him out of the poo. The potential for disaster is greater, although that's an aside.
Absolutely agree with all of that Chris, but there is a point where (when out of control) physics and the laws of monentum become your enemy in a car more so than on a bike.
Assuming there isn't a brick wall or telegraph pole or something similar waiting to collect the rider who has parted company with his machine, his deceleration will be markedly less sudden (and safer) than that the car driver or co-driver could expect!