I don’t think one need assume they are dabbling in dispensationalism in order to recognize that they were wrong to be antisemitic. It’s not an atonement, it’s an apology. Long overdue, seems to me.
The article uses the pejorative term "replacement theology" to describe traditional Christian beliefs. That is dispensationalist.
Anti-Semitism and NAZI sympathies are represented as the consequence of traditional Christianity. Atonement is a form of reconciliation after an offense. The Amish group is seeks atonement for Anti-Semitism and NAZI sympathies by rejecting traditional Christian beliefs.