SDA, in my experience, have a very narrow view of history and tend to think of the USA and Western Europe as being the prophetic center of the universe.
Once I was talking to an SDA about Orthodoxy and her history, and he said, “If what you’re saying is true, what does this do to the Adventist interpretation of Bible prophecy?” I replied, “You said it; I didn’t. What i’ve told you can be verified in secular encyclopedias. I challenge you to see if what I’m telling you is true, and if it is, are you willing to re-evaluate the Adventist interpretation of Bible prophecy?” He was silent for a minute and replied, “No.”
In other words, don’t confuse him with facts; his mind is already made up.
FWIW, if an SDA becomes Orthodox, s/he most be received by canonical Orthodox Baptism, and NOT by Chrismation.