Yup, forgot that aspect but the martial race theory have been abandoned officially in 1947, there's nothing officially that stops anyone to apply and write the exams and sit in interview for commissioned posts.
For the martial race theory's affect, the Mulle Jat, Pathans, Syeds, Rangars etc are still underrepresented and were officially the martial races, moreover the prevalence of martial races is in non-commissioned positions and non-martial but well off castes like Khatris, Parsis even Jews have served and are still serving one of the top posts through commissioned posts.
I don't think so, Muslims are likely to write exams than enroll as jawans to join the Army but maybe wrong on this.