Sounds like a good plan to keep people engaged and interested.
This TAM thing is awesome. People all sweating the cap need to relax and consider that the "cap" is already basically a floor. Mechanisms to remove players worth being paid more than the cap figures allow and forcing money into the league quality are brilliant. You're looking at an additional $10mm invested into player wages in the next 5 years (more with expansion) just on the basis of this single mechanism.
As others have noted, making minimum salaries higher and wasting money on a higher cap is a shitty proposition for the league and U.S. players. Hell, other than Mix, we don't have an American I'd pay 6 figures for.
And it seems pretty obvious to me that this isn't the Jones situation. This is something likely everyone knew was coming. Pinning or crediting too much of any of this or other more-Jones-esque decisions to Garber is just kidding yourself. The owners make the decisions. Does he have ideas? I'm sure. But nothing like this gets done in this league without most of the owners agreeing to it. Go read about the unfairness of Dempsey's signing. Shit happens because the owners want to make the league better and seize opportunities. To expect complete clairvoyance as to what mechanism will be needed to meet a new opportunity to improve the league is unreasonable.
You can't demand of any team that they release their transfer budget. No reason to keep expecting it from MLS. It's self-defeating, bad business.