Firstly, nobody refers to either any Elder Scrolls game or the series as "scrolls", it just doesn't happen. Secondly, the Elder Scrolls part of the name tends to be subordinate to whatever the name of the current game is. These both make it extremely, extremely unlikely that anyone would ever seriously confuse Scrolls as being a Bethesda game within the Elder Scrolls series. Thirdly, the games are nothing alike: Elder Scrolls games are first person single player RPGs, it's similar to Fallout 3, Red Dead Redemption, and Grand Theft Auto, except in a medieval fantasy setting; Scrolls is a multiplayer trading card game with "tactical" elements, it's similar to Magic: The Gathering, Culdcept Saga, or Yu-Gi-Oh, nobody could possibly confuse the two even if they only managed to see 10 milliseconds of game play.
The only people who could conceivably be confused into accidentally buying Scrolls when they meant to buy Skyrim would either have so little idea of what Skyrim was or so little grasp on reality that they would be equally likely to buy Halo or a bag of M&Ms.
This lawsuit is like if Blizzard were to sue the company that makes "Raft Wars" because it was infringing on the "Warcraft" trademark.