I of course know nothing about this person, but I find it truly bizarre - and, yes, grossly inconsiderate of the co-workers - that anyone can just up and disappear from a job like that without at least cluing some people in. Not to mention, how do you ever expect to become employed again?
Wow--that thought just reminded me of this incident from about 23 years ago: This person signed on as music director for a show at one of our local theaters, led the first two or three rehearsals, and disappeared. They just never showed up again, or even called to convey the message that they couldn't follow through with it for whatever reason, or offer any kind of apology...to the theater management or to anyone else. One of the cast members with experience took over (I was rehearsal and performing pianist but was unequipped to do that myself then) and all was eventually well, but to my knowledge, none of use ever saw or heard from this person ever again. Ah, community theater...