Is it against Muslim law to be killed by Infidels? so why did they have to bury Osama Bin Ladin at sea?

His family in Saudia Arabia refused his body for burial. The US didn't want to bury his body on land for fear that it would become a shrine of sorts for other radical Islamists to want to visit. Burying him at sea is acceptible in Islam, and now there will be no final resting place technically for him.