Not a lawyer either, but although I agree with that interpretation, I'm not sure where Class C Misdemeanor comes from.
The article states that:
Cameron County prosecutors pushed for Class C felony charges of “terroristic threat” and argued for two more weeks of detention. Instead, Judge Adela Kowalski-Garza ordered a safety risk evaluation and conditional release home until his hearing November 8.
I used your link to search for "terroristic threat," and found this statute:
There is no mention of a Class C Misdemeanor in that statute; so I'm not sure what the Texas Observer is talking about.
Again, not a lawyer, but by my reading of 22.07, it seems like this ridiculous charge would be a Class A Misdemeanor under:
Subsection (a)(2):
(a) A person commits an offense if he threatens to commit any offense involving violence to any person or property with intent to:
...
(2) place any person in fear of imminent serious bodily injury;
...
With the penalty described in subsection (c)(2):
(c) An offense under Subsection (a)(2) is a Class B misdemeanor, except that the offense is a Class A misdemeanor if the offense:
...
(2) is committed against a public servant.
Class A misdemeanors carry both a fine up to $4000 and jail time up to 1 year.