Does Work Study income reduce 529-reimbursable expenses the same as grants?

[BelknapPoint]

If, say, she earns $1K from a work study job in a semester, are we required to reduce any 529 reimbursement by 1K?

No.

IIRC, work study monies are not taxable income. if she has $1000 in work study, she will have no tax liability

Work-study wages generally are taxable earnings, although they are typically not subject to payroll (FICA) taxes.