Gesturing at literature as a defense without engaging in the literature is, and always has been, an endorsement of the ideas in the literature and not "intellectual engagement".

If the other founder went "here's his blog post where he discusses <these ideas> that potentially justify the support for this party without just being support for right right hate and other political positions" that would be intellectual engagement. That's not what occurred here. What occurred here was a vague gesture in the direction of far right writing as if that somehow justifies the concept.