Truth be told, I don't know what Rav Falk holds. If anyone knows him personally, I'd love to hear what he has to say. But that aside, it's not really about Rav Falk, because (as Joseph pointed out), even if Rav Falk does not hold that way, there almost certainly is someone who does.
Upon reflection, I realize that to whomever holds that position, I must be a really dangerous deviant. After all, I am routinely (multiple times daily) guilty of the following breaches of tznius according to that position:
- If a woman holds a door open for me, I actually have the nerve to say "thank you" to her.
- If I bump into a woman on the subway, or step on her toe, or hit her with my bag, I actually say "I'm sorry."
- When I get on the bus in the morning and evening, I say "good morning" or "good evening" to the bus driver -- regardless of the gender of the driver.
- When I pass people on Shabbos* I say "Good Shabbos" to them if they appear to be Jewish, or "good morning/afternoon/evening" to them if they don't appear to be Jewish.
- When I walk into the local grocery, I say good morning, etc. to the person behind the counter, who just as often is a woman as is a man.
- I say hello to the person at a checkout counter when I buy something -- and yes, often times that person is a woman.
I suppose that with these multiple lapses of tznius that I commit daily, there are those in some communities who would view me as downright lecherous.
In the comments to my previous post, Joseph expressed a concern that such common courtesy can lead to inapporopriate behavior. In his viewpoint (and others, I suppose) the fact that a torrid affair could arise from a "thank you" is enough grounds to prohibit it. But in truth, I think he vastly overstates the danger. The odds of a simple "thank you" leading to something inappropriate are so remote as to be negligble. Does it happen? I'm sure it does sometimes -- but not enough to make a general rule of rudeness about it. Making such a rule falls right into the "If Only One..." fallacy.
* I do so sometimes on weekdays too, but more often people are rushing on weekdays and don't want to be bothered.