I immediately redflag anyone who advertises themselves as "ex-company". It shows a lack of character, judgment, and, probably, actual results/contributions. Likewise, it shows that they're probably not a particularly independent thinker - they're just following the herd of people who describe themselves like that (whose ven diagram surely overlaps considerably with people who describe themselves as "creatives" - as if a car mechanic working on a rusty bolt or a kindergarten teacher, or anyone else, is not creative.

Moreover, if the ex company was so wonderful and they were so integral to it, why aren't they still there? If they did something truly important, why not just advertise that (and I'm putting aside here qualms about overt advertising rather than something more subtle, authentic, organic).