Sorry for the delay in replying to this post. I wanted to triple check the rules before making any statements or suggestions. Speaking honestly, I've always found the rules around spirits crossing over, with their environment and manifestation conditions, flow charts ect very confusing. So I wanted to make sure I have it correct before replying (this is further complicated by the fact that the term "Reaching" means different things for Uratha than it does for spirits!).

I agree that in a way it would make sense for Uratha to be able to Reach without a Locus, if spirits are able to do it, but I think the mechanic is meant to allow for spirits to cross over more easily as a way of justifying the likelihood of Uratha having to police spirits who have crossed over.

However, these are the rules (in my understanding) so that we can address how the pack wants to manage things.
-Uratha can only cross the Gauntlet (Reach) at a Locus.
-Spirits exist within the Hisil, but can influence the world of flesh from the other side of the gauntlet (Reaching for spirits). This requires one point of Essence. At a Locus they get a dice benefit to try to perform a reaching task across the gauntlet, but otherwise they get a penalty to their dice pool based on the Gauntlet's strength
-A spirit can try to cross the Gauntlet "bodily". Doing so is called "Gauntlet Breaching" as opposed to "Reaching". A spirit can only do this is an area in which they have resonant essence (which would not be the nursery IMHO... though perhaps the spirit could create resonance in the area by say making everything ill and rotting via numina). Furthermore, they must make a dice roll the same as reaching which is affected by gauntlet strength. When a spirit Gauntlet Breaches, it ends up "In Twilight", meaning it still can't be seen by mortal, passes through walls, and can't directly affect things.
#When HWOB was chasing the uratha and actively crossed over and manifested, it did this in the sewer tunnels that had been heavily "chewed out" by the Beshilu, creating a weak gauntlet and the requisite resonant condition.
-Once a spirit is in twilight, if it wants to become physically corporate, it must then "Manifest" costing another 3 essence. This does not require a dice roll.

I hope what I have posted is helpful in the team's game planning. Please let me know if you have more questions, or are ready to begin. Though we are still waiting on Subzero, if he/she does not post soon, I'm happy to get things started.