What you’re seeing in the corner of the casket in the photo in the front of the church at the visitation is the metal lid brace. It only goes a short ways out from the lid. The higher part on the”headboard edge” in the Diocese image goes about halfway across the “headboard” and creates a square corner in the profile.
Some here can't project an idea and then expand on it. It's just not in their DNA. Sometimes that's the only way you get anywhere.
To suspect foul play in a suspicious airplane crash where the biggest player is the only one killed is not conspiratorial, IMHO. Laying out the scenario and then proving it is often what we do here. It's never easy and sometimes controversial especially on FR.
You have to make an assertion and then go about the hard work of proving it.
Not everyone can do that as is all too obvious.