Are you asking if it's racist, or if they deserve a ban for racism?
Racism is an auto punish for me.
Is it racist?
I can't see the whole chat log (I don't think Riot likes Summoner names being posted, either, not entirely sure), but I would think that crosses the line. Some will say yes, others no. It depends on how the person who it was directed at felt. If they felt offended, then yeah I guess it's racist.
I mean, if someone hates Obama, suddenly they hate all black people and are racists, right?...so sure. (giggles, pokes the crowd)