HollowNotionUniversity professors in Texas are suing the state over ‘unconstitutional’ TikTok ban
RaphaelCongress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
If they were forbidden from installing the app on their personal devices, I'd agree with you. However, the ban is on installing it on government devices, so it's their right to make that rule.
Also, if they really have to watch TikTok on government provided devices, they can watch through Firefox or Chrome or Safari. I'm not seeing any issue at all here.