Well you can just turn the code 180 degrees from the linked question and problem solved.
Just kidding.
I would start with getting the current page slug, using that slug search for a category that has that slug, if found, redirect to it
add_action('template_redirect', 'bt_redirect_page_to_category');
function bt_redirect_page_to_category () {
// if we are not in page, no need to run the code
if (!is_page()) return;
// get current page object
global $post;
// get page slug
$slug = $post->post_name;
// the term taxonomy
$taxonomy = 'category';
// get category
// you can use get_category_by_slug(), but I prefer get_term_by()
$category = get_term_by('slug', $slug, $taxonomy);
// if no category found, no need to continue with the code
if (empty($category)) return;
// found category so we can redirect
if ( wp_safe_redirect( get_term_link( $category, $taxonomy ), 301 ) ) {
exit;
}
}