If your gming, it's up to you.
But I'd have ally spirits be no less screwed than any other spirit. (more reason to not go, and that is how Ghosty likes it). Now, many spirits in Denver are likely immune/ not so effected, but I imagine their formulae take Zebulon into consideration, and Ghosty and Zeb are both going to be very protective of that data: if someone could track Zeb's mood via spirits, they may be able to learn enough to start to influence those moods..something Ghosty certainly doesn't want, so the "no spirits" dictate would be very aggressively enforced.
I loved the old Denver boxed set: no real truth given, even the gm book had 3 variations for major npcs so the GM could choose what was "true" on that specific table. If you have a player that has invested heavily in an ally then you would have different parameters for gming Denver. Maybe losing the ally and having to deal with Snowball or the ZDF would be fun? Or not. Happy gaming!