If they bless same sex marriage they are breaking the law of the land and if they don't they are not following their church doctrine which they swear to keep. It come down to which is higher the government or the church. After God na Government, but who is the representative of God on earth u may ask, is the church or religious bodies we all believe and look up to for morality.
Hence this interpretation of what is and what is not by the Bishop trying shield themselves from both the church and the law of the land. At this point, just give to ceaser what belong to him and God what belong to him
“Catholic Bishops Clarify Church Position on Same-sex Marriage - THISDAY Newspapers”