MGA did Takfeer on the Muslims of the world many times, this is the second instance. And remember, MGA’s definition of hell is different, so he calls everyone as Kafirs and Mushriks, however, they can still make it to MGA’s heaven.
“…It is rude to say that Jesus didn’t die, it is indeed shirk al-akbar [major polytheism].” (Roohani Khazain, Volume 22, Haqiqat-Ul-Wahi, Mirza Ghulam Ahmad, p.660)
MGA did Takfeer on Muslims. It is confirmed.