I can only speak for our guild, but we do factor in that stuff-We would expect an applicant who never saw some heroic only mechanic to fuck up once or twice.
But keep in mind the guild he referenced was double his previous progression-Unless he went from 2 to 4 heroic, I'd wager that was more than a couple weeks post progression kill.
I guess it all depends on the person, back when my old guilds would die for whatever reason, I always found progression more stressful as an applicant than farm content. Partially because they figured out how they do it, so I could talk to people of similar roles for advice.