So currently you can’t post in #suggestions until you’re TL2 (15 days visited).
This is to keep bad posts out (with some degree of success), though the catch is that whenever a TL3 moves a post into suggestions, the original poster can no longer edit or reply to their own suggestion. TL3s also don’t have merge permissions, so in the worst case we end up with stuff like this:
To fix this, TL1 users (10 minutes readtime, 30 posts read, 5 topics entered) should be allowed to reply in suggestions, but not post threads.
I’m not sure if this stops the user from editing their original post, but at the very least they get to respond to people, and TL4s can edit their post for them where appropriate (say, quoting something they said in a reply).