But this is not even only about the flag but majorly about 1xbit campaign participants that people can click on their 1xbit signature to register on 1xbit.
The only way that could be prevented is if scams were moderated and removed. Since we know that won't happen, anyone can click on those. After all, if someone is so reckless to click on some link that leads him to unknown betting site and he immediately deposits money without checking whether that site is legit (all you have to find out that is to google "is 1xbit scam?"), he will lose the money at some other place, even if he is protected here on bitcointalk.
With that being said, I see no harm if trust scores were visible to guests.