The American Academy of Sleep Medicine (AASM) is correct in what they are saying when they said that
It is possible that using CPAP could increase the risk of spreading the virus to others around you.
If you are suffering from COVID-19 and use a CPAP machine, the air around you is sucked into the machine and blown out of the mask. Excess air pressure is blown out of outlet holes in the elbow joint between the tubing and mask. This can carry the COVID-19 pathogen out with it at force, spreading it further around the room.
Take this elbow joint as example, used on my CPAP mask.
When you take where the idea of using oxygen and air supplies comes from
... if demand continues to grow, hospitals could use sleep apnea machines, suggests George Washington University Law professor John Banzhaf
This quote from the 2nd website (an article supposedly checked by an MD in Coronavirus Today) highlights that this is a hypothesis from a non medical professor. He may have experience working within the field of medicine but he is a medical negligence lawyer, not a medical practitioner, as highlighted by his George Washington University Law page
The idea of using an oxygen and air supply is "thinking outside the box" but not viable from my knowledge of CPAP/APAP machines. CPAP and APAP machines take air from the surrounding air through a filter on the side of the machine.
Take for example, my CPAP machine air intake photographed in this image
There is no way of connecting a bottled oxygen and air supply to this air inlet.
Using oxygen and air supply between the machine and mask
You said in the comments:
I checked that as well and there is an easy way to connect oxygen. If the CPAP is not oxygen compatible, you can add an oxygen bleed adaptor between the machine tubing and the mask tubing.
If you are looking to add oxygen within the air supplied to the patient, you are correct that you can connect an adaptor between the machine and the tubing to the mask.
If you are wanting to maintain a specific oxygen concentration, the way CPAP/APAP machines work is different to hospital ICU (Intensive Care Unit) ventilators.
Ventilators employed in NIV [Non-Invasive Ventilation] range from ICU ventilators with full monitoring and alarm systems normally employed in the intubated patient, to light weight, free standing devices with limited alarm systems specifically designed for non-invasive respiratory support. Life support ICU ventilators separate the inspiratory and expiratory gas mixtures. This prevents rebreathing and allows monitoring of inspiratory pressure and exhaled minute ventilation on which monitoring and alarm limits are based (British Thoracic Society Standards of Care Committee, 2002).
British Thoracic Society Standards of Care Committee. (2002). Non-invasive ventilation in acute respiratory failure. Thorax, 57(3), 192. DOI: 10.1136/thorax.57.3.192 PMCID: PMC1746282