Interesting gavra – who is your RY?
I am surprised if it could be classified as bal tosif. Rabbi Falk is not adding mitzvos to the Torah nor adding details to a particular mitzva.
Whether you agree with him or not, he is just putting forward his interpretation of ‘Hatzea Leches’ and assessing in a practical way what modes of dress can cause improper thoughts and attract undue attention.
I would venture to say that to classify that as bal tosif is actually being ‘ Megaleh Ponim Batorah Shelo Kehalacha’ a common pitfall when exaggeratedly disagreeing with someone else’s views.