Is there a word for a person who won't speak up when they don't want to do something, or who makes excuses about doing something without actually coming out and saying they dont want to?
Equivocator. It means "to use ambiguous or unclear expressions to avoid commitment, or to mislead" (Dictionary.com).
From merriam webster: adjective: passive 1. accepting or allowing what happens or what others do, without active response or resistance.
"the women were portrayed as passive victims"
synonyms: submissive, acquiescent, unresisting, yielding, unassertive, non-resistant, compliant, complaisant, pliant, resigned, obedient, docile, tractable, malleable, pliable, meek, subdued, deferential, forbearing, long-suffering, patient, lamblike, non-violent, supine