ZD, firstly, that’s not true about Satmar. More importantly, there is a huge range of people who would fall under the chareidi label. Satmar are not the only chareidim.
Modern Orthodox ranges farther to the left, which is why there are more dropouts.
We’re talking about people who keep Shabbos, and want their kids to, but sadly many don’t. Rabbi Gordimer (and others) are correct to sound the alarm.