LW folk generally are proponents of Vat-Meat.
On one hand, I agree with you that it's probably not that effective to specifically court the LW demographic. That said, EA-Animal-Rights people are usually in favor of vat-grown meat (there are companies working on it. To my knowledge they are not seeking donations (although Modern Meadow is hiring, if you happen to have relevant skills)
"expose existing cattle/chicken abuse in farms and slaughterhouses" is a mainstay vegan tactic. Robbie's article was prompted by Brienne's article which was specifically arguing against videos that did that (especially if they use additional emotional manipulation tactics)
Just as a data point: the emotional manipulation tactics (i.e graphic videos) were effective against me. (Mostly because I was unfamiliar with the process before. I didn't know what happened) They tend to be effective in people especially sensitive to graphic images, I think, but I realize that in general it's not a tremendously effective way across the population spectrum. If it was, everyone (or at least everyone who has watched those videos) would probably be vegetarian at this point. This is not the case.
I'm currently unconvinced either way on this matter. However, enough arguments have been raised that I think this is worth the time of every reader to think a good deal about.
http://nothingismere.com/2014/11/12/inhuman-altruism-inferential-gap-or-motivational-gap/