He's not really that old, I checked his youtube profile and he is in his mid 50s. I mean okay he has white hair but would you call Iommi a grandpa? or Glenn Tipton?
I dunno maybe it's just me but the tag, 'grandpa' seems a bit pejorative in this sense...
Like he might have white hair (it's not secret that many elder metal musicians dye their hair, in fact Lemmy recently said that he if didn't dye his hair he'd look like Willie Nelson yet I still don't consider Lemmy a grandpa) ... I dunno just how I'm seeing it I guess...