I'm a flight attendant, but not for UAL. I think what the FA meant on the PA was that if you had another UA flight (UA flies up and down the west coast!) and missed it, the company would provide accomodation accordingly. You probably mistaken the announcement.

For future reference, ask the FA what exactly do they mean on the PA. Although UA and SQ are in the same alliance, but if you have seperate tickets's PNR between the int'l and domestic (split tickets) then UA's responsibility ended upon arrival in LAX. UA definately would not be responsible for the accomodation in LAX because their job was done at that point (to get you to LAX).