Fine to disagree but I stated the reason.
The breaker is there to protect as equipment much as possible. The way to do that is put at the source. Then it protects your wiring, the TIU, more wiring to the track, and so on. This is a basic electrical convention. Even modern recent autos are putting fuses right in the battery terminal these days for this reason.
And, given the cost of TIUs these days, you'd think you would want to provide as much protection against all faults as possible.
