Energy was acquired by Harmon/Infinity. They probably decided that Energy had a better sub rep than Infinity so put the Energy name on their new sub.
Harmon/Infinity is an interesting company. They have occasionally supported some very low pricing on Energy Speakers and subs, just as they do for the Infinity Primus P363. I'm not sure how this practice fits into their overall business model. They may figure that if they can get their P363's in the hands of young audiophiles, they will buy upscale Infinities later in life. Perhaps they are doing the same with Energy (but I don't think Energy had any products that were budget/value oriented - low quality finish, etc.)?