Check the Wayback Machine and you’ll find that Merriam-Webster’s definition of “preference” said nothing about the term being offensive
as of September 28, the last time the page was archived. Today the label “offensive”
has been attached, with this note about usage:
Usage of Preference
The term preference as used to refer to sexual orientation is widely considered offensive in its implied suggestion that a person can choose who they are sexually or romantically attracted to.
It’s … strange that the alleged offensiveness of the term came to M-W’s attention only recently if it’s “widely considered” to be taboo.
As for when, precisely, the definition was altered, presumably only the editors know. But there is this:
Looks like the page was updated on the very same day that
Mazie Hirono went after Barrett for using the term “sexual preference” at her confirmation hearing. Fancy that.