USD: Pixar
OpenSubdiv: Pixar
jss-api-gem: Pixar
Munki: WDAS
Reposado: WDAS
SeExpr: WDAS
Ptex: WDAS
Partio: WDAS
Dynamica: WDAS
BRDF Explorer: WDAS
OpenEXR: ILM
Alembic: ILM and Sony Imageworks
So which one of these is not a Disney project, considering they all originated from and are maintained by Disney engineers?
Sony gave it to ILM to start using, and then open-sourced it.
I'd quibble that while ILM and Pixar employees are technically now Disney employees, it's not as if they work for Walt Disney Animation Studios directly, so it's not as clear cut as you make out.
ILM and Pixar are very much Disney employees though, as in employees of the wider Walt Disney Company (which this page is for; the specific page for WDAS is here [1]). If you get a Silver Pass and your pay comes from TWDC's bank account, I'm pretty sure you are a Disney employee. WDAS, Pixar, and ILM are all just individual subsidiaries under the wider TWDC umbrella.