Actually, the opposite holds true to a certain extent.
I tend to give less merit to a good post by a Legendary, especially when I'm low on sMerit.
Simply because he won't need it as much as an aspiring Newbie / Jr. / ... / Hero.

OTOH, many Legendaries tend to make more relevant, insightful, helpful posts.
Simply because they tend to be a lot more experienced and usually are well beyond the "chatter childhood" of new users.