I know the Huff Post article says he's referring to "Congress" which makes you think the denominator is, roughly, as you calculated. But they referenced the quote as being from a Tulsa World article which states:
"It is the reason, he said, he left the Senate.
“Five or six others have (long COVID), but I’m the only one who admits it,” Inhofe said during a recent interview."
This makes me believe the actual denominator is ~100.