IANAL, I just read legal blogs from time to time, so take this as a simple blanket explanation. Without details of the case it’s hard to say. IP law gets insanely complex. It’s also very likely that this animator was told the case was not actionable by an attorney some years ago, but then talked to a someone else with a different legal opinion more recently. Then there’s the cost of litigation, which will be extreme given this is Disney, so it probably took time to get the money together for a retainer, and financial risk of a loss and counter-suit makes it risky.