…because the Ashkenazim wouldn’t be yotzei…”The Rabbaim there apparently hold that Sephardim listening to Ashkenazi leining are not yotzei as well”
If this is indeed the Rabbaim’s psak, it is an incorrect psak. It cannot stand up to any serious scrutiny, and it is very unfortunate that these Rabbaim came to this wrong conclusion. V’shari lehu marah.