overwhelming fear of my son sneaking out so I turned his lock

So his door locks from the outside at night when he's sleeping and he has an alarm on his door as well as all of the other doors but my husband snores SO loud that I don't know if I'd hear them! My nephew (now 15) snuck out at my son's age (3) and walked to my/my parents home which was 2 streets away and one of them being the Main Street in our town. Because of that i have had this overwhelming fear it would happen with my son who is autistic and is just now beginning to talk. I've received nasty remarks from my sister that his lock is like that (the mother of my nephew) you'd think she'd understand! Now I saw on the news today a 3 year old boy wandered out at night into the cold. He couldn't get back in the house and was found dead on the porch 😭 (rip sweetheart). Is it wrong for me to have the lock like that? I even go in at night and check on him, he wakes up in the middle of the night at least twice and he knocks and I go in. I would never just lock my child in a room for no reason... but I'm not willing to risk the chance you know?