That's understandable. The USA tends to do the same--that is, trying to separate economic foreign relations from security concerns. See our leaders' sometimes shameful treatment against Taiwan in favor of China's vanity and penchant for expansionism, for example.
Even military action against Iran would not be likely to interrupt the pipeline construction. If India wants to follow through with the pipeline deal, it will happen.
Actually the biggest impediment (for India) from this pipeline may notbe a US attack/invasion of Iran,which but India & Pakistan may tacitly support,but Pakistan's unreliability as well as instability in Baluchistan through which such a pipeline will have to pass through.Till now India has been accused of helping Baluch insurgents against the Pakistani army,but if a trilateral pipeline takes off,the insurgents will see it as a betrayal.
Did I mention that the Baluch insurgents are experts in blowing up Pakistani pipelines!!!!