A lawprof friend of mine mentioned to me that he thought that "philandering" stemmed from Philander C. Knox, the late 19th-century and early 20th-century U.S. politician. This reminded me of the many such words said to be created from the names of people -- hooker (supposedly from Gen. Hooker), sideburn (from Gen. Burnside), cardigan (from the Earl of Cardigan, also a military man), crapper (supposedly from the plumber and toilet improver Thomas Crapper), and sandwich (from the Earl of Sandwich).
Here's what the Oxford English Dictionary tells me about these: Sideburn, cardigan, and sandwich, the OED reports, are indeed named (or, as to "sandwich," "said to be named") after the people. Not so for philandering, attested back to the 1700s, and stemming simply from "philo-" and "andro-," "loving or fond of men" (though the OED doesn't report any homosexual connotation). Likewise, the OED reports that "crapper" comes from "crap," which is attested to when Thomas Crapper was ten years old. And "hooker" appears in 1845; the story about the hooker-Hooker connection refers to Hooker's supposed tolerance for prostitute camp followers during the Civil War. It's possible that the term "hooker" was popularized in part by the Hooker story -- I don't know whether this is so -- but it certainly wasn't created as a result of Hooker's actions.