Deregister Podcast Tags

I’d like to use a custom taxonomy for my podcasts called “topics” instead of “Tags”. Specifically because it appears by default SSP is applying the WP Core post_tag to Episodes instead of a custom tag (e.g. podcast_tag), which really would be preferrable because the tags of posts really are different and have different purposes, but when you add a tag in Podcasts you add a tag in Posts as well currently.

Longterm, I’d love to see a real separation between podcast tags, and post tags.

But in the meantime, is there a way to simply deregister tags only for the podcast post type? I have tried the following without success:

// Remove tags support from posts
function myprefix_unregister_tags() {
    unregister_taxonomy_for_object_type('post_tag', 'podcast');
}
add_action('init', 'myprefix_unregister_tags');

Perhaps I’m not loading that function early enough, I’m not sure.

Any help and guidance on this front is appreciated. Thank you!