This is a myth conservatives want you to believe. In reality, they use the constitution and laws to protect but not bind themselves, while at the same time to bind but not protect others. In the state of Virginia today access to pornographic sites without ID verification was made illegal by Republicans. This example or any of the BS Desantis has pulled recently in Florida shows when aligned with their goals there is no hesitation to pass anti-constitutional measures.

In the case of student loans - public education helps the out group, so any justification (constitutional or otherwise) will be used to attack it.