Sure, this is an informal environment, but Casey is acting as an individual working on an issue in their own time. The MS employee above is acting as a defacto

Sure, this is an informal environment, but Casey is acting as an individual working on an issue in their own time. The MS employee above is acting as a defacto representative of MS whenever they speak about their work in public. Casey is also responding to unprofessionalism initiated by MS. (Though admittedly the "they started it" defense isn't a great one)