Is there a hole in the pipe under the welded on nut? I can't tell from the photos. From your photos I can't tell if there is a hole in the pipe or not, but it clearly looks like the bolt is plenty long. If there is no hole or it's too small of a hole a thread tap will not fix it. You cannot drill the hole out from the nut size as you will end up drilling out the threads on the nut to make a hole big enough (if there is no hole or it's too small). If there is a hole, but it's too small for the bolt to fit in, you could file a taper on the end of the bolt as there is plenty of thread left and the nut it is threading into is actually raised above the pipe body.
If there is no hold in the pipe, send it back via the Amazon return process. Should not cost you postage either once you start that process online.