BSY and his party in Karnataka have ensured that BJP becomes the single largest party. The party has then staked claim to form the government with the Governor. As per the rules of law of the land, the Constitution allows the Governor to consider offering the first chance to the single largest party. Hence there are no constitutional issues with BJP trying to form the government. The only issue remains is about the numerical strength of the government and that the BJP has to prove its majority in the state assembly.
The BJP has to get the support of more than 50% of the MLAs present in the house on the day of floor test. With 105 MLAs in their hand if the attendance is less than 209 on the day of the floor test then the BJP can prove its majority and continue to run the government within the rules of Constitution. The opposition has to ensure that it gets all of its MLAs and have to ensure that their MLAs during the voting donot vote for BJP for various issues.
The non-BJP MLA can vote for BJP for various issues. Tired of being treated like cattle shifting from one place to another in the hope of grabbing power to a set of families, the MLAs may ditch their party during the secret ballot. The MLAs can claim to be not having sound health on the day of voting and they simply walk out of the assembly to be absent during the floor test inspite of a whip being issued by their respective parties and help BSY in winning the floor test. Amith Shah might have thought about several other possibilities.
As long as the rule of constitution is not broken, there is no justification needed as to why the BJP is forming the government. The bigots and power hungry opposition have virtually killed the democracy by subverting the rule of law several times in the past and have made it into an art form. The BJP is not doing any of those and if anything unconstitutional issue is found, the slaves of dynasty have a pliant judiciary willing to hear cases even in the middle of night and try their luck.
BSY should form the government because he can and it is within his constitutional right. All others who are crying about murder of constitution and what not can take a secular, judicial hike.
Picture Credit: @BSYBJP