Not completely true. Reload-on-Start has two parts 1) Load the Data Provider, 2) Reload from Data Provider when starting LASR. The second works for all tables existing on the Data Provider. The "participating" isn't that binary considering this, it's just the first part that is limited.
Since this don't make complete sense we now have asked SAS Support if this is correct and advice using DI Studio Transform that loads LASR directly. The answer is obviously currently to manually load the Data Provider from the DI Jobs. Just making a point that the Transform could be doing this as an Option "Load Reload-on-Start Data Provider Library" or even automatically when Reload is activated in Metadata.
Thank you all for your help in understanding this. I will update with any informational answers from the Support.