Indian procurement is a mess, but it might be argued that a Soryu purchase makes sense, to provide a submarine with longer range & endurance than their other conventional types.
That argument goes out of the window if one assumes they're going to get a fleet of SSNs, but given the success rate of indigenous Indian developments, it could be sensible insurance.
Or it might be just incoherent procurement. Sometimes, Indian military procurement is so crazy that if you made it up, noone would believe you. For example, I remember the offer of ex-RN Sea Harriers, which was turned down on the grounds that they were offered without AIM-120 & their Blue Vixen radars. The Indians claimed that they were useless without radars & missiles - despite: -
They knew that AIM-120 needed US approval to sell, & if granted, India could buy it direct, so they didn't need any from UK stocks.
India had already signed a contract with Israel to upgrade its existing Sea Harrier fleet with EL/M-2032 radars & equip them with Derby missiles, & that contract could easily have been extended to cover extra aircraft. This would have been preferable logistically & operationally to a fleet of 20 or so aircraft with two different radars & two BVR missile types.
The only explanation I can see for the failure to buy the ex-FAA SHARs is pure incompetence - unless it was because the MoD doesn't pay bribes.
