I don’t know what the substance was in the bulk toiletry and it really doesn’t matter. That these get tampered with in practice should be enough to stop the project in its tracks. And 5000 Marriott points as an apology for this is genuinely offensive.
How can the hotel expect to charge for a room that is so poorly cared for by housekeeping, and that jeopardizes a guest’s health by allowing the toiletries to be compromised in this way?