Well I'm really not ignoring that, and I definitely understand that guys are cutting a ridiculous amount these days. It is bizarre that just a couple weeks ago he was supposed to be dialed in for a 155 fight and now he is ready to roll at 170 though?
The other point here is that its not as simple as "just don't cut". Not only would he want to be bigger to fight at 155 (170), but he will want to strip away the fat anyway to fight there. This article gets into a little more of that and was written more about his fight at 155:
http://www.boxingnewsonline.net/cono...-moving-on-up/
Obviously Diaz thinks he is on steroids, or has at least brought it up. Its an enormous move up and it is basically all of a sudden. If he shows up at the weigh-ins and is much less than 170, that is a different story (not sure how far below you can be according to the rules though?), but I can't be the only observer who questions a jump in fighting weight of 25lbs in 12 weeks.