CBD's partial and weak binding, in my imagination, suggests it sorta lingers, impeding, but not preventing, other molecules binding (e.g. to the CB2 receptor), so that theory fits in as far as I make sense of it.
As an additional aside,
I have this other characterisation which I'm fond of (usually to help the uninitiated get a handle on it), that THC is like the rowdy nuisance stressed drunk at the party, causing a ruckus when alone, but when his girlfriend CBD is there too, she keeps him calm and helpful, like a perfect party guest.
If Ignorance is bliss, give me agony.
Time flys when you're not in pain or prison.
Educate yourself so you may educate others.
We are psychenauts, and we are not afraid.