That simply doesn't make sense. The OrbComm satellite was almost sure to burn up if they didn't launch it from a higher orbit. If the only risk was to the satellite, then go high or go home.
The problem was a (very small, almost surely overstated, but there nonetheless) risk to the ISS. From Orbcomm's press release: "the rocket did not comply with a preplanned International Space Station (ISS) safety gate to allow it to execute the second burn."
if there was not at least a 99 percent chance that the rocket had enough fuel to complete the burn