I'm guessing your gut is telling you this is bovine ordure.
I'll leave it to those with more biology to debunk the "chelated calcium cures all ills" theory in detail. For me, the following lines on that website would be enough to send me running:
Like many equine diseases there has been very little proper academic research on the two debilitating conditions Cushing’s and Laminitis. There is a well-established drug treatment for Cushing’s and while that approach works well for some animals it can have severe side-effects in others. Some vets are even considering a surgical approach which suggests that some are not comfortable with drug therapy as an option.
As we know, there are several peer-reviewed studies on PPID and more on laminitis. As we also know, severe side effects from pergolide treatment are extremely rare. And finally, I am at a loss to imagine what a 'surgical approach' to PPID might be--it does seem that if a vet removed the pituitary gland, this would effectively kill the horse.
So if these people get even basic facts wrong about a condition they are claiming to treat, that suggests to me they are at best ignorant, at worst, charlatans.
I'd say your gut is correct.
Maxine and Indy (PPID) and Dangles (PPID)
Canberra, Australia 2010