It's terminology they used during conversations. On the site they also call it "accelerator".
Don't focus on semantics. As is the case for patents, where the blah-blah doesn't matter, only the claims matter, the only thing that matters here is the contract you sign. We could call this thing "A trip to Disneyland" and still the contract terms would rule the relationship.
Semantics is the meaning of what you say. It isn't some subordinate type of communication; it is fundamental to communication. If we don't focus on semantics, we don't focus on the meaning of what you said, and we aren't able to judge whether or not what you've said is true.
You used a word, presumably to make a factual statement about a thing. We need to know why you think the word applies given the context in order to know what you're trying to communicate.
If you don't want to communicate with people, you're free not to. But you did try to communicate with people, so don't be surprised when they ask you to clarify what you said.
And, yes, the semantics part is deriving a meaning that does not exist or is irrelevant from my use of the term "incubator" (which, as I explained, the contract authors used with me during email conversations).
It's about the contract.