Nitish Kumar is clear about his arguments as illustrated in his interview with arnab today.
He says caste is enshrined in the constitution through caste reservations hence he wants focus on caste in this election. This is what the constitution fathers wanted.
However he says cow slaughter is enshrined in the constitution through beef bans hence he wants no focus be given on the issue in this election. This is what the constitution fathers wanted.
So why did Lalu and Nitish comment on cow slaughter of they wanted to avoid making it centerstage in the election? Because, he says, everybody is free to do so.
And why are you opposing Mohan Bhagwat's comment on caste based reservation. Because, he says, he cannot be free to say whatever he wants.
He says this election is about local issues.
However in his very next sentence he goes on to say that Bihar elections is a matter of referendum on BJP which has a government at the center for 15 months.. But it is not a referendum on his own governance or the lack of it for the past 5 years.
There is just so much clarity of thought (as displayed above) and unity - that Nitish makes sure he avoided even naming any of his "allies" of this election!