I'm an experienced amateur astronomer, and I have a degree in the science, and I've seen (and been thoroughly annoyed by) many Iridium flares. But these are relatively nearby (several hundred miles away?). Geostationary (these guys did not move) birds are many thousands of miles away. I dont think these are chance reflections. These objects are roughly two orders of magnitude further away than Iridium, so by inverse square law, they should be approximately four orders of magnitude fainter (say three to make allowances for specular reflection. Could they be solar reflections off geostationary satellites?
Possibly... but highly unlikely, by a factor of a thousand. They are definitely not Iridium.

Hank