The author of the quote in the OP has no clue what "tenure-track" means.
He/she claims that it means "tenure for everyone", which is absurdly false. Tenure-track merely means that the professor's are full time and that their job performance is rigorously evaluated each of their first 5 years, after which they essentially fired or given "tenure", which merely means that they cannot be fired just for saying something the offends the sensibilities of a couple of students or of politicians, but rather must be shown incompetent or doing harm to the mission of the University.
Sander's sensible requirement solves several problems. It will result in more full time positions and fewer part time adjunct positions in which faculty are paid less than $20 per hour to teach 1-2 courses and are hired and rehired on a semester to semester basis. This results in profs will low pay, no health care or retirement packages, low motivation, and that are never on campus, except the few hours per week they teach. Also, it is common for such profs with no ties to the University to suddenly quit right before or during a semester. In addition, those part timers have no facilities to do any research and cannot train graduate students.
As to not allowing the additional funds to go toward yet more administration, this is also very wise and would improve student education, in contradiction to the claim that it...
Nice Squirrel said:
destroys student support services
Faculty per student ratios are near or below what they were 20 years ago. In contrast, administrator to student ratios are 10 times higher, and yet this has done nothing to improve the quality of education or provide tangible assistance to students that help them graduate. Most of what administration does is useless bullshit, forming committees to select committees to think about ways they can create more administrative work and time wasting forms and regulations for faculty to follow.
The potential major flaw with Sander's plan is that he doesn't seem to give enough recognition to the reality that R-1 Universities are the bedrock of basic science in the US, where tenure-track faculty do and should be spending time conducting research, advancing knowledge in their field, and training future scientists at the graduate level (most of which happens outside of "classes" and in the lab). But that is actually a minor amendment to his proposal. Overall, greater funding of full time faculty positions would benefit this research goal.