Sorry for the delay in response.
Edge browser is different from other browsers like Chrome or Firefox - it is more like a Windows service, than actual application. So, adding Edge as option to list of browsers would require large amount of programming. Since Edge does not support RoboForm, antivirus and other useful tools, I'd assume not too many users would want to use Edge with SL. So, creating a new version of SL to add Edge into browsers list would be very low priority.
I've found some kind of workaround - how to use Edge instead of one of legacy browsers, like Flock. If you OK with extensive registry editing and command file creation, I can provide step-by-step instructions.
Note: running Edge from Sweepstakes List neither warranted, nor supported.