Mesae, I hate to break it to you but it is quite possible that the site's author is correct and that the stabilizer is lifting positively when at the aft end of the allowable spectrum.

If you do some checks around here you'll find that unlike full sized aircraft that are mandated to limit their CG's to fairly forward values our models can and do operate with further aft limits and the stabilizers are often, no, actually most commonly operate with a positive lift value.

Based on the fact that this is how the full sized stuff is generally set up it's no wonder that the instructional books are written the way they are. They are just discussing the parameters as they are normally encountered in the full sized world and with the generally accepted full sized aircraft range.

It all comes down to how stable we need our aircraft to be. In the full sized world the needs for stability are great and this shows up in relatively far foward CG's in order to provide a very linear and highly self restorative reaction to pitch displacements. However our models often toss all this aside in the quest for higher performance and more pattern like model flight response to pitch variations.

Even in the full sized world I suspect that if you do a check into it you'll find that the aerobatic pilots in their Sukois and Extras are operating with CG's that have more in common with our models than they do with commercial or the usual private aviation types.