If you are open about being poly in your life, and can handle the possible consequences of being out, then you are very free to be your 'regular' self here. If you want to use your usual Internet non de plumes, go for it.
The emphasis on anonymity is to get people to think about their situation and how being open as poly may impact them. For too many people the impacts could be very negative - job loss, child custody issues, loss of friends or family. This board is searchable by Google and so one's user names and postings are public. That means if one is not careful, uses the same user name as other sites, gives too many identifying details, it is possible for others to figure out who you are.
But if you are already open and have few consequences to worry about if outed, then fly your freak flag proudly!
Disclaimer: I mean 'freak' kindly as in 'let us non-mainstream folks hang out and be awesome together'. And define non-mainstream however you want.