I guess perhaps to help keep yeast in check - but a) if the problem is yeast, then it's already past the point of ACV helping and b) Anti-protozoal meds do not cause yeast to propagate so there's no need to be proactive about fighting a yeast infection when treating for protozoa.
I actually think that Cocci is a much more reasonable assumption.. *ducks and hides*

All that being said - I have Worm Away (but I don't think you need it, so I really wouldn't want to sell it to you), but Ronex has been back ordered from MB for well over a year. I believe Misty should carry the Vetafarm equivalent which is Ronivet-S?
ACV you can get from any health food store or Vitamin Shoppe (look for Bragg's Apple Cider Vinegar... it can't hurt to have it but I don't think you need it for this bird.. you'd be better off sticking to a good probiotic, it would be more beneficial on the whole).