I think that you are overstretching the reality. Pakistan has expressed regret over its actions in Bangladesh as correctly pointed out earlier by Agnostic Muslim. If not the political leadership in uncertain terms then certainly a large portion of its academics and its ruling elite. Even my father in law, a rabid Pakistani hater, believes that the Pakistani Hindus who came into India were being opportunistic with unrealistic expectations.
I appreciate the bridge you provide in this forum...and lot of insight you give (love reading lot of it, and hope you do share more).
Expressing regret is not really substitute for declassifying the commission report and coming clean (based on your own state's investigation)...that too this downstream in time.
If Pakistani political elite (and these are mostly military fellows in end still when you peel layers away), truly "regret" it...what is there to keep classified then?
If larger Pakistani people also truly regret it (in enough number and are in position to do something)....what is to stop them putting pressure to get the full story released from own state investigation?
I am just telling you what are basic preconditions (its my opinion) to have something of a moral ground shaped up for further analysis on this matter, given Pakistan is first of all now a 95% homogeneous (by religion its founded on) and officially allies itself with this religion (Islam) whereas India by same religious standard is 78% homogeneous (at best) and allies itself with nothing religion-wise (It is Secular republic).
Otherwise we simply rather (and frankly ought to) listen more to our actual peers in the world....for actual consistency and credibility in the argument.
As for why Pakistani Hindus did come and set up, maybe there is some opportunism there sure...but there is also actual grievance with Pakistani society and state too.
And why none of the reverse for even 1 indian muslim (of the minority of them that supposedly, and I stress the supposedly.... love/ally with Pakistan more than India)....if things have been so bad, are so bad or going to get so bad for them (relatively speaking as they see it).
Neither do they flee to BD (in fact from BD given looser porous border situation we see tons of BD muslims having come to India illegally).
They (Indian muslims) always in the end make their stand in India.
A cursory examination of their best leaders like Owaisi will tell you why quite quickly.