Perfume on my Mind wrote:My guess is that starting a sentence with whom is as objective as he gets.
Clever! I never thought of that.
I suspect, though, that he will continue to misuse both "who" and "whom", just like some people persist in confusing "then" with "than" and "who's" with "whose" and confusing "their", "there" and "they're" with each other, no matter how often anyone tries to correct them. Apparently, for some people, improper grammar usage, once it gets started, becomes a deeply ingrained habit that is hard for them to break (or brake).

I also suspect that tendency is stronger with the types who cling to hard core, irrational beliefs, despite any amount of contrary evidence. They can be as resistant to correction of their faulty grammar usage as they are to correction of their cherished delusions.
ETA: It is also possible that he thought that "whom" is the plural form of "who", and didn't realize or forgot that "who" and "whom" can both be either singular or plural.