I'm not 100% certain but I don't think so. When at regular room temperature the item needs to be able to hold its own shape. In a hot place (warm room temperature) butter can't hold its own shape.
Doing a Google search on "butter on an airplane", it doesn't seem that butter isn't permitted. Several website state that butter is consider to be a paste/gel by TSA, but I don't have any first had experience with this.