The flag will only get activated if it gets supported by a DT member. If a random user creates a flag and no DT user supports it (like in this case), then it doesn't mean anything. The flag has no effect in your account, so just ignore it.
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.
How much DT support needs for a flag?