Navy couldn't risk the salvage operation when they couldn't still get the total pictures and as the sub is inside the harbor,we couldn't risk while there is live torpedos and missiles in there..so,Navy wants to play safe by using professional expertise..
So you are saying India has no professional expertise? May be with couple more ships blown up India can become an expert in salvaging sunken ships, as India is quite adept in salvaging crashed fighter planes due to the vast experience in that department.