In relation to the 1st pref requirement:
I couldn't see anywhere about it being a
requirement to have unimelb biomed as 1st preference and I would be surprised if they are allowed to do that given that in course interviews they aren't allowed to ask if you have the course as your 1st preference. Sometimes they say something like "have the course as your first preference" more generally because you need to enrol in the course in order to receive the scholarship. The only other thing I can think of is that your school has decided (even though this is
not in the eligibility advice) that they will only nominate a student who has the course as their first pref. Your school, unlike unis you apply to, can see your preference list.
School nominations for this scholarship close 30 November.
If you get a med interview:
Scholarship offer or not, unimelb can't prevent you from going to a monash med interview. Getting a scholarship offer cannot lock you into a course. If you were offered an interview do NOT turn it down unless you decide you don't want monash med anymore. Of course, if you do end up enrolling in monash med rather than unimelb biomed you won't get the unimelb scholarship.
Anecdotally, I was offered a biomed scholars scholarship from monash but I had global challenges as a higher preference and enrolled in global challenges rather than biomed in the end. In the end I didn't get the scholarship because I didn't enrol in the biomed course but if I hadn't gotten into a higher preferenced course I would've been able to study biomed with the scholarship.
Hopefully this makes sense and helps!
info links:
https://scholarships.unimelb.edu.au/about-scholarships/melbourne-principals-scholarshiphttps://scholarships.unimelb.edu.au/awards/melbourne-principals-scholarship