To be honest, yes it does. Dark/fuller hair in older men isn't that unusual - I have older male relatives with hair that has greyed to this sort of pattern and with this sort of fullness, plus as other posters have said, who the hell would bother paying thousands of pounds for a wig with a built-in developing bald spot? It would take 'mimicking real life' a touch too far in the quest to be convincing - and would defeat the object somewhat!
It's an old joke re Terry - one that I think he has actually perpetuated himself in the past - and an urban myth becomes fact.
Of course it is a rug, i have seen his Wedding photo from more than 50 years ago, and his hair was thinning then.