I'm pretty sure there are counters (plural) to Time Stands Still. Perfect Defences have a counter, DR probably has a counter, Hugareida-based defences have a counter... each form of attack we output has it's own weakness as well. Whether the Champion has an applicable counter is in question, though. We ourselves don't (yet).
I think we could counter TSS with our own TSS, honestly. Our amazing armor plus Slowing Slog up going full blast would also be a soft counter to some degree vs. a lot of opponents depending on how hard they hit (we could survive what we're throwing at this guy with that, for instance...we'd take 17 damage after DR, which would get through our armor and Frenzy, but only do one actual Endurance damage), though without our armor it'd kill us anyway.
But that said, I tend to agree that this guy having a hard counter to TSS is
very unlikely given his seeming combat role. High DR is likely, but would not actually let him survive in most cases...he'd need DR 12 and Endurance+Frenzy 22+ to survive and he is
not wearing armor which makes that a pretty unlikely number. Heck, he needs a minimum of DR 6 and DR+Endurance+Frenzy of 22+ just to survive Threadcutter (a more plausible number, to be sure, but still a very high one).
Someone like Heima Smiles or Blurryblade or maybe even Skoll The Hasty? They might have a counter for TSS. This guy? Nah, I don't think so, barring the DR idea, and while I think he has high DR, I don't think it's quite
that high.