Regardless of whether or not the guardian can be literally anyone, your argument falls apart the instant we realize that the incapacitated person retains the right to counsel, but by virtue of their incapacity, the guardian is empowered to exercise that right on their behalf - that's what guardians are for, to exercise rights on behalf of others who are not capable of so doing for themselves. It most certainly does not mandate lawyers for incapacitated people, particularly lawyers imposed regardless of the patient's or guardian's wishes. "The concept still applies" - please. That penumbra will be emanating all over you before you know it.
No it doesn't. The guardian is prohibited from some activities. PERIOD.