That quote has nothing to do with the fact that it was condemned pre-Vatican II to pray with heretics and the like. I do understand that post-Vatican II it’s all about False Kumbaya Ecumenism.
Yes, “Saint” (who was it that canonized him again? Oh, that’s right the non-Catholic “pope” leading the Sin-od....Francis) JPII had a habit of praying with heretics and the like (Assisi!). And here we are using his teachings to call another a heretic.
Ironic indeed.
Throw Veritatis Splendor in the trash?
Participation in non-Catholic religious services has always been considered unlawful but that's not the same as "praying" is it? Saying a prayer with a non-Catholic has never been proscribed has it?
Furthermore, the Church has always distinguished between formal and material heresy, which is why the "invincible ignorance" mentioned in the quote becomes important. I can't see how those with whom JPII prayed can be considered formal heretics, or apostates.
We can argue about whether Assisi was wise but I doubt it was illicit.