Get rid of it! I tried to do LabLab and Soybean mix this year and that was my result as well. I went to war on it in July and did a complete burn down. No way I am letting that crap go to seed. I am wondering if the cold wet spring brought the pigweed? Never had to deal with it before...
Not sure if those those seeds are viable yet but they soon will be. You could be fighting that for a while. It would be nice to cut and bale it to get those seeds off the plot. Then let the bales heat up/compost to kill all those seeds.
Yep,mow now and then spray with interline or something other than gly.Deer will eat it better than about anything when little.I bet you worked your ground and it was in the seed bank.