Yes, of course, because then it would take a further Act of Parliament to amend it, assuming there was no other Henry VIII power lying around that could be used to repeal it. Assuming that does not happen, you need an Act of Parliament to change an Act of Parliament, so you would have to go through that process. The Government might, of course, have a majority in the Commons and the Lords to proceed with that, but certainly it is a longer process involving more public discussion. Bills get more scrutiny than statutory instruments and are usually more open to public debate than the statutory instruments process is. It is not an absolute guarantee, but it is a relative guarantee if you put something in primary legislation compared with secondary legislation.