I'm sorry but that statement is simply not true and for multiple reasons.
1. You have a splash lubricated crankcase on the Bauer Junior 11. As with many other small oil lubricated portable compressors. Some of the larger units may even have an oil pump known as a gearoter pump but again all types of oil lubricated compressor are subject to RPM.
Too slow an RPM and the oil slinger doesn't fling enough oil up from out of the sump and onto the moving parts or by another example take the gearoter mechanism type on the Oceanic when running too slow this hasn't got enough RPM to create enough oil pressure to pump the oil out of the sump and up onto the moving parts the crankshaft bearings, conrod, guide cylinders and pistons etc if running too slow.
2. The inclination of the pump on a rolling deck is another hugely damaging consideration for small portable compressors on a yacht.
Further take say the Coltri MCH6 and their new ICON range these only have a 5 degree and a 6 degree angle of inclination in a stationary position on land any more in one plane and there is in effect no oil in the sump and that coupled with a low RPM is a huge bill a comin. Take the other angles on a yacht the pitch and roll aspects and too much oil slugs up with a hydraulic lock risk conversely the other extreme of the angle incline is oil starvation.
3. Also you need to achieve sufficient cooling and the fan is directly affected by the RPM
Again for offshore we change the pitch angle of the fan blades and the number of fan blades depending on the ambient air temperatures location flow and pressure but again critically the RPM
So I trust you appreciate that while there is granted a very small narrow band range of RPM available it is critical not to under run or over run these limiting factors in a typical oil lubricated recreational sports scuba compressor.