Wanted to get my two cents IBTL.

Air Carrier Access Act allows for this sort of preboarding as long as you alert the GA prior to boarding.

Lawfully you don’t even need to alert them as to why, and practically Delta doesn’t make you even do it. Only AA has challenged me.

Delta has been great about their blanket “extra time or assistance,” pledge to preboarding customers.

Delta’s been fabulous, but the most resistance has come from other passengers that lack knowledge of the law or may just be plain ignorant that preboarding isn’t always a visible maladity.