The power of an atomic weapon is nothing compared to the power unleashed by a volcano.
Unless the explosion were to occur at some highly critical point, I doubt it would do anything. Further, I also doubt there is a highly critical point that could trigger the earth's mechanisms to begin volcanic activity or that anyone could even get to it without a massive effort.
Lots of mass in the form of under-pressure magma must already be in place before the event can begin. A bomb isn't going to attract pressurized magma.
To me it seems that the "scientific" community believes a lot of their own crap.