While we have seen a recent flurry of colleges/universities that have dropped COVID-19 vaccine mandates, we are still hovering at around 1000 colleges that mandate primary series vaccines, just under 250 colleges that mandate one booster dose and 21 colleges that specifically mandate the bivalent booster which means that if a student already took a monovalent booster that student would need to take a second booster to be up-to-date as per the college COVID-19 vaccine policy.
I don't think Purdue or Baylor were prohibited from putting in vaccine mandates. Purdue is a public university in the state of Indiana much like Indiana University Bloomington which does have a covid-19 vaccine requirement.
As for Baylor, it is a private university in Texas akin to Rice but my understanding is that Rice had covid-19 vaccine requirements at least for employees but I think there was a mandate for students at some point.
Penn State may also have been allowed to mandate vaccines for students since there seemed to be employee mandates at some point due to the possible upcoming OSHA law which was struck down by the Supreme Court:
I could be incorrect about these schools being allowed to mandate vaccines. If they were allowed but didn't, then I expect it is mostly due to the student body being less willing to abide by mandates than student bodies at other institutions. This may be the reason for re-education as the students were expressing "wrong-think". Some of the schools where the governors prohibited covid-19 vaccine mandates are the state schools in Florida, Georgia and Texas. I checked your list and didn't spot particularly onerous restrictions but realize this list may miss some information. If it's accurate, then it is possible that the students in these schools were not punished because the schools saw the fault lying with politicians rather than their own student and faculty body expressing "wrong-think".
I don't think Purdue or Baylor were prohibited from putting in vaccine mandates. Purdue is a public university in the state of Indiana much like Indiana University Bloomington which does have a covid-19 vaccine requirement.
https://www.iu.edu/covid/index.html
As for Baylor, it is a private university in Texas akin to Rice but my understanding is that Rice had covid-19 vaccine requirements at least for employees but I think there was a mandate for students at some point.
https://www.houstonchronicle.com/news/houston-texas/houston/article/Rice-keeps-employee-vaccine-requirement-despite-16692558.php
Penn State may also have been allowed to mandate vaccines for students since there seemed to be employee mandates at some point due to the possible upcoming OSHA law which was struck down by the Supreme Court:
https://virusinfo.psu.edu/faq/story/is-penn-state-making-the-covid-19-vaccine-mandatory-for-employees-or-students/
I could be incorrect about these schools being allowed to mandate vaccines. If they were allowed but didn't, then I expect it is mostly due to the student body being less willing to abide by mandates than student bodies at other institutions. This may be the reason for re-education as the students were expressing "wrong-think". Some of the schools where the governors prohibited covid-19 vaccine mandates are the state schools in Florida, Georgia and Texas. I checked your list and didn't spot particularly onerous restrictions but realize this list may miss some information. If it's accurate, then it is possible that the students in these schools were not punished because the schools saw the fault lying with politicians rather than their own student and faculty body expressing "wrong-think".