Dear Sivanandan,
A probationer is also a regular employee of the organization. Only difference is that he is kept on vigil for a short period so as to have an objective assessment of his suitability for his job as well as the organization culture. So the purpose of probation is not to send him out but only to evaluate the chances of his retention in the organization as its full member. However, in matters like leave sanction, discretion is exercised by managements by way of caution to limit it to pro-rata basis only during probation period. Marriage is an important event in one's life and as such it can not be postponed for want of leave from work and also the quantum of leave required for it may exceed his leave at his credit. Therefore, consider asking him to go on LLP which would consequently extend his probation period proportionately.