It’s interesting alright.
If the “% Elemental MG Absorbed” values are correct then people, and examine.com, are quite incorrect about bioavailability.
The only thing I would note is that just because Oxide has a higher Elemental Mg does not really mean much, as most people take different forms of Mg based on their elemental Mg weight, rather than the actual weight of the salt. Really all it means is you have to take less pills/powder to get the same amount of Mg.
There are 7 types of Magnesium & my brother who is really into his nutrition (he’s autistic & it’s his ‘thing’ believes they all need to be taken at once, on an empty stomach, right before bed, for maximum absorption. Any magnesium on it’s own is not going to be anywhere near as bioavailable or useful to the body. Just passing on what I’ve been told!