You might be using custom trust list, in my case, with default trust, Bitcoin_Arena seems to be supporting the flag, he is a DT member according to Default Trust.
Yes, the flag is supported by one DT2 member, therefore it is valid and shown to newbies and guests who didn't explicitly distrust him (which probably not a single newbie has).
How much DT support needs for a flag?
A type 1 (newbie warning) flag - which it is in this case - requires more people (in your personal trust list; e.g. DT) supporting it than opposing.
A type 2/3 flag requires 3 more people supporting than opposing.