Yes, that is a concern. But encouragement to participate in any language the community member chooses is the official policy of the forums as it stands today. Furthermore, Ted's thoughts on this topic are spelled out in the previously-linked thread:
In other words, the current policy has been considered in light of the potential moderation difficulties that it raises. Discussion around changing this policy is, IMO, appropriate in another thread. I'd like to refocus this thread on discussion around how to more-fully realize the current policy of encouraging participation in any language that community members choose to use.