The states have the right to regulate business within their State.
They can make it illegal to for people in Texas to use such a web site, and the can make it illegal for a company to run such a business.
The Federal Government can overrule that in the interest of their power "To regulate commerce with foreign nations, and among the several states, and with the Indian tribes".
The Courts have granted the Federal Government broad powers that it's doubtful that the authors of the Constitution envisioned. However, I've never seen the courts prohibit the States from legislating something just because funds might travel across State boundaries. However, they do appear to allow federal law to supersede State law on such issues.
No, they have the power to regulate the taking of animals. The taking of game was regulated by the Crown in England. When the United States was established, all the crown powers, save those specifically granted to the Federal government and those prohibited to the states, devolved on the states.
States are free to make such laws within their own states, and that's what they are doing in this case.
All they need ban is the taking of game by remote control, it matters not where the "remote" is located.
That said, while the practice is despicable, and is not hunting, a person should be able to slaughter his own livestock in any manner that does not constitute animal cruelty.
I do like the suggestion that the technology be applied to the Jihadis though, but what would one use for "bait"? Maybe a young virgin or a cartoon of old Mo?