Yes, so he could admit to conspiring to engage in unarmed housebreaking and/or grand theft auto, which would be felonies outside the DC felony murder rule. I'd say that with what we know so far the evidence does point to weapons being acquired on-scene rather than brought there (though we don't know about the knife in the trash as to whether it was brought there or came from there), so there potentially could be a defense there of saying he was there for an unarmed home invasion and stealing cars but it was others who subsequently got armed and did the killing, so even though he'd be admitting a felony it wouldn't be one that falls under felony murder. I don't know that it would be a successful defense, but depending on what the evidence shows it may not be a defense that has no hope of success. The defense already has the prosecution insisting there were others involved, so they're going to have specifically prove he personally committed one or more of the underlying felonies (I think he did, but so far I haven't heard evidence showing that he specifically did rather than a member of the group did one or more of the qualifying felonies).
Hope his fingerprint or DNA is on some of the duct tape. If he had a knife in his backpack (he always seems to have a knife with him) = felony. If he restrained them = kidnapping = felony. Robbery = felony. Set the fire = arson = felony. If DW isn't talking, they're going to have a hard time finding someone else to pin all of these actions on. If he went in through the front door, wouldn't GTA qualify as robbery?
I think once he spent the night, he gave up his chance to plea he was just there to steal cars.