Prime Minister Modi is entitled to his opinion that Sardar Patel would have made a better Prime Minister than Pundit Nehru. There is also nothing wrong in he expressing it in a speech, in the Parliament.
Who knows? Perhaps India might have taken a different course with Sardar Patel as the PM.
However, India or Congress Party cannot go back in time travel and change the history. It is too late to replace Nehru with Patel and test Modi's hypothesis!
I too have a similar opinion.
Had BJP opted for any decent human being, to be the PM instead of Narendra Modi, it would have been beneficial to India!
A human being.......
who will not display his or her lack of decency in every speech,
who will not abandon his or her spouse,
who will not use one's own mother as a prop in public relation photo shoots,
who will not lie about his/her educational qualification,
who will not lie on matters of his/her life even in sworn affidavits,
who will not use blaming his/her illustrious predecessors as the only answer to any Parliamentary criticism,
who will not maintain strategic silence when his/her foot soldiers are indulging in riots or lynchings,
who will not conduct diplomacy in a way to benefit only his/her cronies,
who will not favour his/her industrialist friends over a time tested organization like HAL,
who will not take ugly U-turns on all the policy matters that he or she used for getting votes,
who will not use the sacrifices or dead bodies of soldiers to getting a few votes,
who will not destroy time tested institutions and conventions without thinking through the consequences and alternates..............
This list can go on, but, I guess, is sufficient for any responsible political party to consider replacing it's nominee for the top job before it is not too late for that party and the Nation!