Engage never stopped selling "MD legal" SBRs on Form 4s. AFAIK.
Now, just because one store kept making them doesn't make it legal. But MSP never shut them down, and they obviously were in the loop.
>29" and copycat compliant are requirements, but that's not too bad to do. At least it's measured with any collapsible stocks all the way out, so you can still get a 10.5"
There are also MD legal pistol configurations which are a possibility if you want a shorter barrel.
Also, if you fill out the apropriate transport paperwork, there's nothing stopping you from taking your MD legal SBR to VA (or another state), assembling it with a shorter barrel upper while there, and returning it to MD legal config before the trip home.
So an SBR lower still has a lot of utility, even if you're limited to 10.5" barrels while in state. You can still own and use shorter barreled uppers if you want to (out of state).