No they generally can't, that only applies in extremely limited circumstances. And I'm pretty sure "ooooppppps" is not one of those circumstances.
Well, you and I both know that to be true in the real world, but his question made me dust off the books. The 35A stuff read broader than I thought it would. Basically says a "general guardian can do all health care stuff except x, y, and z (all not pertinent, things like sterilization, etc.), but can do all other things" Saw some secondary stuff from SOG that specifically included withholding LPM's. I was surprised.
By contrast, Chapter 90 (re the D.D.N.D., a/k/a "Living Will") requires physician to join in on the triggering diagnosis (and it contains a conflicts clause giving 90 preference over 32A (HCPOA) in the event of conflict (but not Chapter 35-Guardianship). So...it isn't nearly as broad as our friend dv7 phrased it, but it was closer than I thought.