you cant just pluck that scripture out of context - jesuss words need to be seen in the wider context of the occasion there spoken otherwise its impossible to interpret what he is meaning by the law - the law he is referring to may well not be the whole list of every single rule the jews followed - he might well be referring back to the ten commandments - consider in luke 13 where jesus heals on the sabbath - is he or isnt he breaking the old testament law regarding working on the sabbath? if by all appearance he is then one can assume by 'the Law' he wasnt including this as part of it
Well beloved lol, I read ("read" that rhymes with "red") the Scripture and nothing in the context says that he meant some particular laws and not all of them; he meant all of the law in Matt. 5:17-19 and I defy anyone to show otherwise.
Jesus did say that he is the Lord of the Sabbath, and he acknowledged as acceptable David's breaking the law when he was hungry, but Jesus still said that he who does ALL of the law is "great." And all of the law includes Deut. 25:5-7:
"(5)If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not marry without unto a stranger: her husband's brother shall go in unto her, and take her to him to wife, and perform the duty of an husband's brother unto her. (6)And it shall be, that the firstborn which she beareth shall succeed in the name of his brother which is dead, that his name be not put out of Israel. (7)And if the man like not to take his brother's wife, then let his brother's wife go up to the gate unto the elders, and say, My husband's brother refuseth to raise up unto his brother a name in Israel, he will not perform the duty of my husband's brother."
So you do find it objectionable if the shoe were on the other foot and your sister was commanded to marry your husband after you die and have children with him?