My guess is that self-swabbing is allowed in the Seattle SCAN study because it is a research study. The SCAN study is super fascinating because it would be crazy unusual under normal times for a research study to return results back to patients; I'm very happy they are able to do that, and it speaks to the severity of this pandemic.
The FDA has recently made clear that no at-home self-collection tests are allowed (for now): https://www.fda.gov/medical-devices/emergency-situations-med...