Just because Valve writes it so doesn't make it so and it has to abide by both regional laws AND regulations. Also if you have read the ToS then you'd also know it has this little bit about if local laws are saying different than what the ToS is, then the stuff will be handled on the basis of the laws case by case, not the ToS.
For example, I live in Finland and we have return rights for 14 days on unsealed online digital/physical products. Steam ToS says, no such things will ever happen but I pursued it and brought up the legistlation and got refund for Crysis Warhead based on Finnish law.
And if the court will find that Valve's practices of denying all the content you have bought through it before the change of ToS is not in line with what should be considered fair treatment of the customer then Valve will be forced to accomodate to that or stop selling in the said country.
And it would be good if the court judged it from customer perspective, because right now Valve has pretty much unlimited rights to the property of the players (And yes, I keep calling it property of the players as long as Steam uses following words: "Buy, Sell, Gift" instead of Rent, Loan or any other words on that category)
Also should be noted that this same case is pushing on the right to resell digital game as ruled by the Supreme Court of EU previously, further reinforcing the customer's right to the product he/she has bought.