In some cities that come to mind, threatening the mayor seems downright patriotic.

If his legal residence is Dammascus, the mother and any other person can file a Notification of Mental Illness with that county. It should promptly be investigated by mental health workers from the county or court to determine whether a civil commitment hearing is indicated, which will lead to a judge determining if he is dangerous and mentally ill. The judge may then put him in a psychaitric hospital for treatment.

In fact, this particular case is even more straightforward, if his mother is really his guardian. Someone needs to tell her she simply needs to have him transported, even against his will, by police, to any hospital in the area with a psychiatric unit. To wit: She can give informed consent to allow doctors in any Oregon hospital to treat him against his will. They'd need to agree he's mentally ill and in need of treatment, of course.

If she as his guardian has called the police or sheriff's office and they tell her "We can't do anything", they are mistaken, and she needs an attorney to explain her rights and duties as a guardian, and their liablities, to the Police or Sherriff. If she recognizes he is a danger to the public, is his guardian, and doesn't enlist the authorities to protect others, she has certain liabilities. If the police or sheriffs don't act in such a situation, and things go bad, they are in trouble. But let's assume they are conscientous and want the best for all involved and the public, and simply don't have good information in this particular case.

Being someone's guardian trumps that person's autonomy to refuse psychiatric care.

Likewise, whomever is holding him now, can take the mother/guardian and her ward (their prisoner) to any hospital ED and drop the charges and remove the cuffs and shackles to make this transition. Similarly, at the upcoming trial, a judge can put him in a psychiatric facility on a Magistrate's Order.

Some of the problems with all the bewilderment about mental health access we are reading about is simple lack of information about how things work and lack of assertiveness to cause the authorities to do what statute and administrative law requires of them.

And, where is Adult Protective Services vis a vis for the case of this 83 year old woman managing a son who sounds this dangerous and mentally ill?

Disclaimer: not an attorney, so may be in error on some of this.