Offensive to Gypsys? They don’t like that name anyway, since it itself is a racial slur derived from Egyptian, or so I read. And best I can tell “gyp” doesn’t have any connection to gypsy at all.
From the OED: “1805 H. K. WHITE in Rem. (1819) I. 209 My bed-maker, whom we call a gyp, from a Greek word signifying a vulture, runs away with everything he can lay his hands on.” Earliest citation is 1750. The first use in the US sense of ‘thief’ is dated 1889, and in the sense of ‘fraudulent action’ 1914, so it could derive from this UK sense.
Much more here.