I would say that it is OK for them to be open to the atmosphere.  The reason to connect them to the manifold is to get filtered air, and to modulate the differential pressure across the valve. At low throttle there would be low pressure in both manifold and rotor housing. I have no idea of the full story of the pressure dynamics over the throttle range.

If the vacuum line is disconnected, the oil being pumped into the rotor housing drop by drop is not spread cross wise along the apex seal. Therefore, the oil will do next to nothing in regard to cooling or lubricating the apex seal.

Based on experience of others, this appears to be an overstatement.  Rotories have run thousands of hours with no air to the nozzles.  There may be some evidence of wear patterns indicating that the tip seal travels some distance (maybe 4-5”) from the point of injection before the oil spreads to the ends of the seals, but I’m not aware of any direct comparison wear with and without the air flow.  Maybe some of our racing friends can have some input on this.

Al