What does immunity to age get you? 'You don't age, you don't get old.' I used to be on the 'oh holy crap that's powerful, immortality whee' bandwagon, until I really started to look at the what it does factor. Without 'age rays' or aging/youth magic, immortality does ... almost nothing. It gives you a good backstory, it gives you a good future-story presuming you survive the more immediate dangers, it means you never have to retire the character due to that one factor - and that's it.
There's a reason why, in HERO System, you can be immortal for 5 measley points - equivalent to 1d6 worth of an attack, which ain't much. Presuming they don't gain the other critter-power immunities immediately, immunity to age is a negligible 'gimmie'. It is interesting to note that the writeup for Harlequin has the Immunities, while the one(s) for Lugh Surehand and Frosty do not. Perhaps those immunities are not innate, and are instead gained from long-term training, magic, or whatever.
In which case, yeah, 'immunity to age' is a gimmie.