I definitely do not mean any criticism of you. My criticism is toward a segment of society that creates “show animals” by breeding to emphasize certain characteristics deemed “desirable” in certain breeds, with little regard for the health and well-being of the resulting animals. Your cat, clearly is a product of this, and a victim of this. You are to be commended for taking this cat in, and providing the extraordinary care that he requires, as a result of the defects that have been carelessly bred into him.
I really became aware of this, a few years ago, when my previous cat passed away, and we got, as his successor, what we thought was a Siamese. On doing a bit of Googling, I found out that the Siamese breed has officially been rather horribly redefined, into a degraded inbred freak breed that probably also suffers from various health issues. My cat is a healthy, happy example of what used to be called a Siamese cat. The International Cat Association (TICA) has now renamed that breed; it is now called a “Thai cat”.
Here is an example of the sort of inbred freak is now called a “Siamese” cat…
Actually, he does, but going by your account of his condition, he probably never looked like that for very long at a time; and even now, with you, he probably looks like that when he has just come from the groomer; and in either instance, quickly goes to the condition in which your pictures show him.