You know, there's something that really bugs me about this twitter conversation.
Using etymology to build a logical argument. It just doesn't work. Contextually, if the people of the time didn't intend for pioneer to be a military term, regardless of its origin it wasn't a military term (also the root for pawn, peon and pioneer all come from the Latin for foot, but its easier to make a word sound bad if you use pawn and peon which have highly negative connotations NOW rather than using foot which doesn't).
Speaking of bad, we refer to tough, admirable people as 'badass'. Which is turn is derived from 'bad' and 'ass'. Bad derives from Middle English (badde - "wicked, depraved") which in turn is believed to derive from Old English bǣddel meaning a "womanly man". Ass derives from arse which in turn derives from proto-Germanic arsaz meaning "buttocks". Therefore using the etymology logic displayed above, calling someone badass today means you think they have womanly buttocks for a man, because the actual intended interpretation of today is irrelevant in the face of where the terms originally derived and their original use.
Anyhow, I don't get why people feel the need to rely on tortuous 'logic' based on word etymology which ignores the actual use of the word at the time of its use and in the context that would be understood at that time. I see it crop up from time to time and just don't get it why people think it supports their arguments.