frank was a freelancer. most (probably all, actually) of the people who write stuff for catalyst's SR4 section are freelancers. they have no ability whatsoever to influence their work directly after it has gone in to catalyst. they can make suggestions, point out errors, etc, but they cannot just edit their work directly.
likewise, they don't work for catalyst, and they therefore have no access to the catalyst website, and cannot (for example) issue errata or provide answers to FAQs on said website. they can, however, (apparently) make statements about how they intended it to be on dumpshock

as far as when frank will be writing for catalyst again, i believe he can be quoted (several times) as saying never. it's not just the difference of opinion (he thinks the matrix rules should be shot repeatedly, buried, and then launched into space, preferrably in the general direction of the Sun. catalyst thinks they should avoid contradicting the core book as much as possible, and that they should therefore stick with the existing matrix rules and expand on them).
basically, frank is currently in school to become a doctor. that kinda takes a lot of time. in fact, you could say that it takes up so much time that there's no fragging way they're going to manage to write much of anything for an RPG company. and i rather expect that when he's done medical school he just might want to, you know, actually be a doctor, as opposed to an RPG freelancer. but that's just speculation