Hello; It is my understanding the bio-film the bb forms sticks well to surfaces. I guess it can be scrubbed off but a strong rinse does not seem to have ever removed much. I do from time to time take a round brush to the insides of the tubes on a filter and scrub away the film that builds up and interferes with water flow.
My guess is that as long as no disinfectant was used that the bb will re-colonize the filter fairly quickly. It is also my take that the bb colonize many other surfaces in a tank so those will still be in place.
I guess that some think the filters and mainly the media are the only place where bb colonize. At least this is the way many comments seem to read in various posts since I joined the forum a few years ago. I can see filters being a place for bb due to regular water flow, but not the only place for sure.
I have given filters and all the parts a good scrub cleaning many times over the decades. Sometimes they just need a good cleaning. Try not to panic. Do a couple of extra WC if you get a mild ammonia spike. Maybe you will not. Good luck