If they share airways with the rest of us then they need TCAS. End of.
Well if you're going to take that line, stop all airliners ever descending through class G airspace, make all aircraft that enter controlled airspace have TCAS and kick out all light GA traffic without TCAS that travels in the airways...to be fair often they are a similar size and weight to VLJs and the only difference is that they are slower and travel at lower altitudes....they share the same departure and arrival paths.
