The "gal" was either not telling you the whole story, or didn't have a clue what she was talking about in the first place. Or maybe she used to work for WildBlue. They had a silly rule like that several years ago. But it was temporary, six months maybe. Once they upgraded the gateway software, that 25' thing went away.
The HN-series of modems have adaptive inroutes and outroutes. The cable length thing is more related to the inroute. The modem varies its output amplitude after considering the real-time quality of the outroute. The algorithm that calculateshow much amplitude to send to the transmitter includes a constant that represents average loss over 25 feet of average approved cable.
But even among the Hughes-approved cables, resistivity varies. So the 25' rule is not hard and fast. It's just a common sense thing. The true test is the actual resistivity test. As long as there is acceptable cable loss relative to the transmitter output rating, the length of the cable run is moot. If you don't have ENOUGH loss, to represent the average 25' run, use use either cheaper cable - or use an appropriate attenuator on the modem TX output.
That's the technical answer. But in the real world, you need to worry more about the MAX run than you do about the MIN run.
//greg//
