That logical connection does not exist. Your cannot start from the premise "India's bases have never been infiltrated" and reach the conclusion "It would be easy to do so in future." For that, you have to add the assertions or premises that this safety record has made India complacent about security.
Similarly, there is no logical connection from the premise "Pakistan's high security bases have been infiltrated in the past" to "Therefore Pakistani assets are much more secure today". You would have to add additional statements that Pak has learnt from its earlier lapses, and is now a lot more vigilant.
Note that I'm not saying that Pakistani military assets are not safe - I'm just pointing out that you cannot reach such a conclusion purely through deductive reasoning - what happens in the real world, whether security has actually improved, such things have to be taken into account.
In any case, stealing a warship is just too far fetched, without massive internal help - like an entire ship's crew (or most of them)being part of the plot. A handful of gunmen cannot hijack a warship from base.
Similarly for nukes, unless there is a large inside play, with many officers being part of it, it is impossible for a few outsiders to load, launch and fire a nuke.