They weren't alone when they reached Rae 5 though, there were already over a hundred Reaver vessels in the System, some of which were pulling asteroids and other large ore deposits with them in preparation for the construction of a massive scale industrial complex.
The sight seemed to amuse Nico more than anyone else, but that might only be because she had hacked into the military transmission encoding and knew what their response was to this sight.
There was no way that they weren't panicking about the fact that literally hundreds of Reaver ships were in the system preparing it to become a major industrial producer. For one, the Nations relied on the Reavers to be their transport vessels between each other, despite many of them officially denying it. For two, nobody in the military knew what exactly it was that they were planning to produce.