You could certainly do that in private but that doesn't mean it's not 'without legal concerns'. But, not shouting about it and not creating a repo called 'openviktor' would probably be a safer bet.

I certainly think the whole idea of IP ownership as related to software will become very interesting from a legal standpoint in the coming years. Personally I think that, over time, the legal challenges will become pretty overwhelming and a sort of legal bankruptcy will be declared at some point in one direction or another (as in, allowing this to happen or making it extremely easy to bring judgement and punishment, similar to spam laws). However, I would not want to be the first to find out, especially in Europe.