This is interesting, and a rare instance where something out of Lucas's mouth seems remotely credible. Was he speaking of the first, or second hospitalization? If it was the second, he's full of shit.
I never believed that Lucas was hospitalized because he was a danger to others, or suicidal, but the "gravely disabled" standard is so high it didn't seem like a good fit either. But it fits, doesn't it? Lucas can't care for himself. It isn't a merely matter of being unable to provide for his basic needs, though he can't. The bare minimum of shit you have to do to keep on living is a struggle for Lucas. This is more than mere laziness (though he's lazy), or the results of being spoiled and unprepared for independence.
I have a tendency to underestimate Lucas's mental health disorders, I suppose. Let this be a reminder to all Wernologists: Lucas Colby Werner experiences auditory and visual hallucinations. And Lucas cannot care for himself as an adult.
I'm curious how much of his 2017 hospital stay was voluntary. WA law requires contested hearings for long term involuntary commitment, but maybe it wan't involuntary after the first few days. Something like: "Well, this place is kind of lame, but I've got nowhere else to go and nothing else to do, and these people will takes my woes seriously and do things for me that I'd otherwise have to do for myself."