'Fearing' determinism (or alien intervention) doesn't make any sense; it's like fearing causality.

People aren't motivated by facts, but by their models of facts. If there isn't a strong desire to produce accurate models, people will accept or reject models based on whether their implications are troubling to them. This is a fallacy related to the appeal to consequences - in this error, people conflate the rejection of a model with making the implications of that model untrue.

For example, refusing to reject the idea of an immortal soul because you don't want people to cease existing, or cutting short one's losses without acquiring the objective because that means the already-committed resources would have been lost "for nothing".

People DO fear the necessarily implications of models, and will accept or reject models because of that fear.