Thank you for reading through it thoroughly and pointing this out! I'm still new and learning Postgres so this is good to know. I will update the post.
I would note that I think the above is a rather minority opinion - while parameterized queries are great for reuse simply using them to guard against SQL injection is still an excellent use of them. If your query is reusable then go for it, but most complex queries tend not to be reusable if they involve optional inputs.