Alternative viewpoint ....
Solo starts are a good confidence builder for students who are deemed competent at start up and taxi (bit of a judgement call for the instructor and some risk possible). Gets student in the mindset of PIC well before solo circuits.
If this student was supervised and deemed competent to follow checklist, start and taxi for fuel (example) - then can't see a problem.
The fact that there was an "incident" means that either the Instructor misjudged the students ability / confidence or the managed and limited risk materialised (unfortunately).
I would say Instructor risk materialised so learning session for the instructor re students ability - STUDENT SHOULD DEFINITELY NOT PAY !
