I'm not saying that ordinary usages of the word "should" are statements of morality, rather the opposite: statements of morality can be translated into ordinary usage, and if they can't they probably aren't coherent statements.

"I am morally obliged to treat this person's injury" "Why?" "Because it would stop their suffering"

Perhaps we prefer to call it a moral statement when it's about other people's utility functions, rather than our own. Then again, we usually don't feel morally obliged to cater to others' preferences except to the extent that we have a preference of our own for their preferences to be satisfied, which, thankfully, most people do.