I agree that Trump did not explicitly tell his supporters to Storm the Capitol, as does Snopes.
The grey area is in the riling up you talk about and the phrasing of the question.
Tell/told is often used to convey meaning rather than literal instructions, so I understand why they have stated this is mixed.
It all feels very post-truth to me and seeing a fact checker endorse this sort of view is absolutely depressing in a way. These are institutions of which there is broad support for making the arbiters of truth on social media for whom truth is subject to subjective interpretation. In which case what's the point of fact checking at all?
This free interpretation of words uses a new (repurposed) trendy term too: "dog whistle". Suddenly you are free to interpret anything one says in the most negative light, just by claiming it's a "dogwhistling" for some group or action you despise.