Well yup I read before that you need to be a full member to get this avatar and it will just apear at your Forun Profile Inform. Base on I experienced you need to actually post topics or replys that must be consist of 2 sentence to make it a good activity but if you make a topic make sure someone will reply so it could be added to your activity. Here dont post  words or a minimum of one sentence thas what I have experienced here.

 
I think so you need it but it will not appear as long as you are still a ranking member.

Here I have made a topic about putting the avatar because I saw a campaign that the campaign maneger literally reply to the participant like like my rank and below that "you may download the avatar here (..link...)"

https://bitcointalk.org/index.php?topic=2101835.msg21006757#msg21006757