Hmm, so SIA downgraded people from Exec Econ to Economy for the affected flights? Any refund for the fare difference? Did you argue with them that you had a connecting flight?
On your question, yes the bulkhead / exit row armrests cannot be raised due to the tray table in the armrests. Not too sure about center rows as there are 5 armrests for 4 tables. I took the exit row at the sides where all 4 armrests cannot be raised.