If I'm wrong then please tell me where so I'll learn something.
You're not wrong, but you are getting in the way of everyone's two minutes hate over patents.
Because [nimrod] has been a well known slur for a long time.
Citation needed.
There's a slang dictionary that lists it as a slang word for "penis" from ~40 years prior to it appearing in Bugs Bunny cartoons, but it doesn't appear to be used in that context in the cartoons. The Online Etymology Dictionary indicates that the term may have been used ironically prior to the cartoons to mock an individual as a poor hunter rather than it's original meaning of a great hunter, but notes that it wasn't until the 80's that it was widely used to mean an idiot, geek, etc.
If you have evidence to suggest otherwise, please let me know. I couldn't find anything to support that claim after a few minutes of Google searching to support that it's been a well known slur (I can't recall hearing it recently so it may have fallen out of favor) outside of the generation that grew up using it. Seems far more likely that a cartoon unintentionally lead to the language shift because it used a reference that children were unlikely to understand as anything other than an insult.
All of that aside, "nimrod" is at worst on the same level as "dork" or "geek" but is probably closer to calling someone a "doo doo head". Only a nimrod would try to insult someone by calling them a nimrod.
Beware of Programmers who carry screwdrivers. -- Leonard Brandwein