There might be some dialect drift going on here. In four decades of playing various keyboard instruments and the violin and singing in choirs, I had never heard anyone use arpeggio to refer to broken chords played out of pitch order until coming into contact with the ukulele and banjo communities. Of course, it’s totally understandable how linguistic communities oriented around instruments that use re-entrant tuning might develop slightly different meanings for technical terms like “arpeggio” and “inversion”, but that doesn’t mean the words have unconditionally changed in meaning. In fact, there are communities where the distinction between “arpeggio” and “broken chord” is useful and has been retained.
(There are also some questions about edge cases that have come up in these discussions, which is somewhat orthogonal to this issue.)
David