Propose: So, the "spy" on the road didn't kill him, he cast a spell on SkeleBro because he wanted to figure out what he is, and is now trying to take over his body/soul(?) because hey, who doesn't want an obedient skeleton minion, and this dream sequence is SkeleBro's chance to subvert the spell.
Or he's dead (again) and this is his last chance to get back to the spawn point, I dunno.