He was originally recruited and then declined to run saying he prefers the private sector.
I think the NRSC is lacking any credible opponent whatsoever, so they asked Pataki just to have his name in the mix so the NRSC can claim to their donors that they're potentially challenging more seats than they are...my same theory as with Hoeven
however that was also my theory with Castle and I ended up with egg on my face
That isn't a well-rooted theory. If you look at the NRSC, they have literally been going all in this cycle. Mark Kirk, Mike Castle, Charlie Crist, Kelly Ayotte, etc. Also, they got rid of Bunning. They've been putting a great deal of effort into netting their high profile candidates. Whether or not Pataki will run remains to be seen, and even then, I'm not sure he could actually win the seat.