Irrelevant. The original
example given is in the dative case, so it has to be “whom”. It’s really as simple as that.
See:
- H. W. Fowler, A Dictionary of Modern English Usage
- Eric Partridge, Usage and Abusage
- Ernest Gowers, The Complete Plain Words
who are unanimous on this point.
After all, these books treat many topics. Without specific reference, one might uncharitably assume that you are attempting to simultaneously misdirect and appeal to authority.
In Gowers, it is chapter 9, “The Handling of Words”, section “Troubles with Pronouns”, subsection 15, “Who and whom”; in the edition I own (Pelican Books 1962, reprinted 1970), that can be found on page 206.