Fluoride is a great idea but for patients undergoing head and neck cancer therapy, chemo and radiation, it is an essential component of maintaing and improving your oral health and prventing your teeth from breaking down. Chlorohexidine 0.12% rinses are also excellent in lowering and controlling periodontal bacteria in individuals with gum disease, ulcers, and compromised immune systems.
Fluoride has been discussed at length in many threads and posts on this site many times. Just type "fluoride" in the search bar and you'll have plenty of information to read.
As for the scaling below 2 mm being detrimental...I do not agree. The average healthy sulcus is 3mm. Bottom line is bacteria, plaque and calculus are toxic to tissue and need to be removed. They are pathogenic to gums and bone and in order to maintain gum and bone health they need to be removed at any depth.

Cheers,
Mike