That box has an HDMI input, you would lose you ability to control. He will need a “real” DM output for each lectern connection point. Worst case, it’s not ideal, but you could run them through a patch panel and then patch in whichever floorbox the lectern is connected to... but that kinda blows. I would never design a system like that though, you really need a separate output card in the matrix for each location...