I am not "offended" by words... (Sticks and stones...etc)
However since we steel guitarists are playing a GUITAR in a different orientation (Flat instead of on it's side) we are often in need of a descriptive term to point out the other instruments that we are talking about.
"armpit" doesn't fully describe it, and I am more inclined to be specific: Tele, Strat, Les Paul, Martin D28, Gibson Hummingbird etc.
ARMPIT GUITAR is just an attempt at "being funny" or "teasing" the other guy. No real harm intended. However:
in this modern "WOKE" society it seems people get offended by words much more often than in the past.
AND TRUTH BE TOLD... we steel guitar players are the real "WEIRDOS" for playing the instrument incorrectly (Starting with the Hawaiian Style of Guitar-just a spanish guitar played on the lap) and then being electrified and made a solid body instrument of different size and shape but still called a "guitar"... I guess we should be able to play nice and respect the instrument from which ours evolved.
JMHO Dom