The employees did not do a great job either it is not unreasonable for them to ask for their money back.
Should police who fail to quell a riot by superior numbers be required to give back their salaries?
To answer your original question umm no I don't think they should their salaries are paid through taxes.
Why would a refund come out of the salaries of campus safety? I can see coming from another source of the universities resources. Milo or his organization paid for security at an guest speaking event. Also I'm not saying that by asking for their money back that they will get it back at this point I don't see that happening, they probably will not get any kind of refund.