I think the expression blood, rain, or horse manure is just an hyperbole be used in that specific circumstance to strongly convey the idea that he was going to run the miniseries at all costs.
- an extravagant statement or figure of speech not intended to be taken literally, as “to wait an eternity.”.
Horse manure is used also metaphorically to indicate a nonsensical idea, but it is not related with the meaning used above.
- (euphemistic) if you describe something such as a statement or idea as horse manure, you are emphasizing that you think it is nonsense ⇒ 'Sounds like horse manure to me, Mikey boy,' said Ballpark., It's all a load of old horse manure. (Collins)