In all of our training activities, the instructor should weigh the benefit of any situation against the risk. Where the risk is judged to outweigh the benefit, then that situation should be avoided.
I would strongly suggest that asking an early solo student to orbit on base, or final is one of those situations.
Whenever I send early solo students in the circuit, at a controlled airfield, I will have agreed with ATC on booking out, that they are not to be asked to orbit on base, or final.
Orbiting in an uncontrolled circuit is very high risk, and should never happen!
MJ
Ps. And make sure they are using the 'Student' c/s prefix. as suggested earlier!