No judgement call, no. But you are asked at GS why you need a DAS, not the diagnosis but what accomodations you need, why the regular line does not work for you.What you have heard is false. My wife used an ECV on our last trip and she used the regular lines if she felt they were ok to navigate. If not we used the DAS return lines. If you go to guest services they will not and CAN NOT ask you why you need it. It gets put on your magic band and those in your party. When you go to DAS entrance at a ride you scan in and they give you a return time. There is no judgement call a CM makes whether you are eligible to enter through DAS.
If it is solely a mobility issue they will, and do, direct someone to using a wheelchair.
But equally, not everyone using an ECV or wheelchair is doing so solely because of a mobility issue. And using one does not exclude you from the DAS.