This sort of "entrapment" is legal in the US? But maybe they wouldn't care. Anyway, wouldn't it be more useful to invest the time, money and energy in facilitating social integration of these individuals. Just asking.
However, from the strictest legal perspective it's questionable how much the entrapment defense could be used in these cases. From a practical perspective much of this is clearcut entrapment. However, from a legal perspective you have folks who very clearly make strong statements saying they are willing to commit acts of terror and then when presented with the opportunity (in an elaborate masquerade put on by federal agents) they follow through. I can't imagine many lawyers salivating at the prospect of defending that.