No write in or 3rd party are permitted.
The choices are either sit out that race or vote for the dim.
You’re correct!
“Independent candidates for federal or state office (including seats in the Mississippi State Legislature) must petition to appear on the ballot. The form of petitions is prescribed by the Secretary of State, and completed petitions must be submitted to the Secretary of State by 5:00 p.m. on March 1. “
Title 23, Chapter 15, Article 13, Part B of the Mississippi Code
Then someone should sue on grounds of disenfranchisement. You should still be able to vote for a candidate of your choice, right?