Yes, we do need legislation to revoke the citizenship of people who violate the constitution or are terrorists. Let me count the ways. You need go no further than the preamble of the constitution which states its purposes as being to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defense, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity.
By this measure, I would put Trump, Lindsey Graham, Mitch McConnell, et al. at the top of the list to have their citizenship revoked so they can be removed from government and not further screw up our nation.