that wall is just ~21.67 BTC. That's not mega at all given the 4693.554 BTC 24 hour volume.
Not to mention the value people should be looking at is the amount of BC represented in the sell walls. If this pace keeps up, by next week a 50BTC sell will not even be a mosquito bite... a week ago it was common to see 100K BC traded at a single price...
Soon that very same trade will be 100BTC... but it will still represent only a very tiny fraction of the BC in circulation - and therefore not a reason for concern.