The fact that he's parking cash in T-bills tells us that he's (or at least Berkshire Hathaway is) nervous about the upcoming election. If he weren't nervous, there are higher yielding places to park cash. That said, T-bill yields are in the 5.5% range right now and that ain't bad.
“I don’t think “controls” is the right word. He is parking cash and it’s gotta go somewhere.”
Agreed, and furthermore, it’s a stretch to say ownership of T-bills means that he controls them.