I've only begun experimenting with Rid-X recently; the filter sludge I hope to eliminate by its use is a PITA to check as it's in the bottom of an opaque container, with about 30 gallons of biomedia situated immediately above. I will be checking for it closely during my next biomedia rinse, which is a year away.
I have no idea if the heterotrophic bacteria in this food will pass through the gastric system of the fish and remain alive and active once they take the "rear exit". But the thread as I recall it is focused on adding the probiotic to the water itself, usually in the filter, to let the little buggers gobble up sludge. Continued regular dosage would imply that these bacteria will not establish and maintain a viable self-sustaining colony and require constant "topping-up". I don't agree that establishing a colony of bacteria...or anything else...requires "constant bombarding". If you are doing that, it implies that the organism in question simply isn't making it on its own; you're creating the equivalent of a put-and-take population rather than a self-sustaining colony. And there are plenty of invasive critters around the globe whose burgeoning populations can be traced back to a single or a few accidental introductions, which were successful enough to get out of control.
The tiny amount of probiotic in the fish food would, I believe, be pretty ineffective on its own, except while it's inside the fish where it might help create a healthier environment. Even if it passes through the fish's gut and is still active, the dilution in the larger volume of tank water would be extreme.
Maybe this might be effective in a new tank, one that hasn't already got a bunch of accumulated sludge in nooks and crannies that can't easily be siphoned and cleaned out? Would regular feeding with this stuff help prevent the formation of that stuff in the first place?
In any case, spooning a septic-tank product into my filter was a huge leap of faith for a cynic like me. I for one won't be feeding what sounds like the fish-food equivalent of yogurt to my fish at the same time; that's just too avant-garde for my blood. Hopefully if someone tries it out they will post and update here.