IANAL, but the statute which gives the federal government jurisdiction over murders committed when the killer crosses state boundaries specifies there must be an aspect of financial consideration, which there does not appear to be in the case.
18 U.S. Code § 1958
(a)
Whoever travels in or causes another (including the intended victim) to travel in interstate or foreign commerce, or uses or causes another (including the intended victim) to use the mail or any
facility of interstate or foreign commerce, with intent that a murder be committed in violation of the laws of any
State or the United
States as consideration for the receipt of, or as consideration for a promise or agreement to pay,
anything of pecuniary value, or who conspires to do so, shall be fined under this title or imprisoned for not more than ten years, or both; and if personal injury results, shall be fined under this title or imprisoned for not more than twenty years, or both; and if death results, shall be punished by death or life imprisonment, or shall be fined not more than $250,000, or both.