Conversation

The phrase "danger to self or others" is a motte and bailey fallacy.

The motte is "murder is so bad that the government should use incarceration in an attempt to reduce murder."

The bailey is "suicide is so bad that the government should use incarceration as a punishment for anyone who even thinks about suicide. Moreover, mental health doctors should be required to play a dual role as both health care providers and cops, who must arrest anyone they suspect of thinking about suicide."

It frequently accompanies another motte and bailey argument, conflating the positions
(Motte) Many creatures benefit from consenual mental health treatment, and in some cases that may include consensually staying overnight in a medical ward.
(bailey): The government should incarcerate some creatures who haven't even been accused of hurting anyone and call it "mental health care."

The supporters of the latter position know it is indefensible, which is why they need to use dishonest arguments equating it with easier-to-defend positions.