http://www.reddit.com/r/Steam/comments/2ji0b3/psa_valve_seems_to_be_cracking_down_on_people/

If steam is cracking down on people selling outside of steam, should those of us that sell for BTC be concerned?

as one smart person said in comments of that post you linked - most likely its just a report thing. Lowballers reporting ppl for no-reasons and so on. Banning ppl who cash out/trade for money would mean killing entire gray market, and i doubt valve is interested in doing that.