As per your advice, I broke the tabs, repeatedly. Oh well. One issue with the driver side is that the vent itself is kind of stuck in some sound dampening material so working back there is tough. There are 4 receptacles on the vent itself and 4 tabs on the outer ring. I managed to break 7 out of 8!! (I stopped just short of perfection.)

A quick solution. On the vent itself there is a channel where the outer chrome ring sits into. This is normally where the chrome outer ring's tabs would then latch onto the vents receptacles. On the outer side of the channel, I applied a piece of electrical tape all the way around on the inside of this channel and folder it over the edge. It required me to cut the tape every 2 inches or so to keep its rounded shape in tact, but the idea was to basically make the channel a fraction of an inch smaller by adding the electrical tape. I then removed that wavy retainer nut and put it aside and gently forced the vent from the inside and the outer ring from the outside together. Holds pretty good and the vent doesn't move under normal use. One strong accidental push might be a problem or heat over time, but its a fix.