The Thundercats reboot was, by most accounts, a tragedy. Unlike most of the property rehashes that account for a worrying amount of modern entertainment, the new Thundercats series was actually pretty well regarded and, from what I saw of it, deserved the praise.
Naturally, this could not last. Cartoon Network had no faith in the series and it never got a second season.
With the show now buried, it seems like a bit of a waste to release an official licensed tie-in. Maybe somebody was hoping it would sell well and reignite interest? That's sadly not going to happen, because Thundercats for the DS is pure, unfettered garbage.