This is my problem with this recent CDC info:
#1) The similar viral load between vaxxed and unvaxxed is measured in the nasal passages. Covid is primarily spread via droplets through coughing, sneezing, and talking. These are NOT passed through the nasal passages, but from the lungs and through the mouth. Again, the source of virus transfer is not the nasal passages, but lungs, throat, and mouth.
#2) The immune system is complex. There are different antibody immune cells in the mucosal system (IgA's) vs. the systemic adaptive system (IgG's) (which activates when antigens enter the blood). The blood antibodies (IgG's) are the ones that are primarily triggered with the vaccine because it's injected directly into this system. And the IgG antibodies in the blood don't get to the mucosal 'surfaces' very well and can't fight against Covid when it initially enters the body through this route - allowing the Delta variant to replicated quickly. However, as soon as those viruses start to invade deeper into the body and enter the blood of a vaxxed person, they are met full-force with a blitzkrieg of IgG's, T's, B's, and NK's ready to kick some ass. This 'loaded gun' readiness prevents the serious symptoms. Of course, with the unvaxxed, the immune system takes some time to 'ramp up' thus allowing the virus to get deeper and do more damage - then the immune system can overcomp in some cases and really cause a mess. On a side note, the mucosal immune system responds better to immunizations administered through the nose, for example. Might be interesting for them to develop a nasal spray vaccination as a one, two punch.
With that said, my point is that similar viral load measured in the nasal passage should be expected for both vaxxed and unvaxxed, but this doesn't necessarily mean that transmission is the same between the 2 groups. I've bounced this off of my brother who's a Bio PhD and he thinks it's a legit argument against re-masking for vaccinated peeps.
Here's a good article I found about this little talked about perspective:
https://www.frontiersin.org/articles/10.3389/fimmu.2020.611337/full