3.3.1.5. College Students. Cadets who are college students living away from their home unit may,with permission of the unit commander, assist their squadron or another CAP unit with special projectsvia online activity. Cadets who make such contributions, even without attending weekly meetings duringthe academic year, satisfy the active participation promotion requirement.
Alternatively, If there is a unit near these college age cadets they can attend their CD, safety, and PT tests there. Just takes an e-mail to the local commander.
They still need CDI. The verbiage you quoted relaxes the physical presence requirement for "active participation", but doesn't change the objective promotion requirements.
Setup a Skype/Google Meet/whatever to allow the cadet to participate in the CD lesson remotely.
Is there public transportation? Uber? Someone from the visited unit? How far is 30 minutes?
How are you satisfying the SDA requirement where the cadet needs to shadow a senior? My sons in the same situation but even as an AFROTC cadet the only way we could think to continue promotions was to visit a local squadron.