Is he from Noo Yawk? That's very characteristic of some neighborhoods in NYC.
Having been raised in NYC, I didn't see anything untoward about that pattern (usually rendered as "I sez").
I did find, when I moved out to Colorado, that my NY accent was pretty off-putting, so maybe that's what you're sensing. (We're probably all on edge lately.)
Only thing that grates on me nowadays? is that rising inflection at the end? of declarative clauses? But I resolve that irk? by mentioning it frequently on APS?
Oh, and Boston accents?
Oh, and marble-mouths on the telephone? and drive-up windows? (But that may be due to age-related presbycousis?)
Oh, and Bernadette Wolowicz's
voice ?
Come to think of it?, I must be a hell of a pissant?
Terry?, 230RN?