I resemble that. Steve, you and I mostly have convergent tastes, so I am sure that you had a pretty nasty steak at TS.
However, your TS experience seems to be much different from my experience, which is informed by stays at ranches on the pampas, dining at roadside BBQs and at top steakhouses in BA. I actually think TS stands up pretty well. I'll also emphasize that the food is markedly better at TS these days, in general, for whatever reason. Now, I have had disappointing meals there in the past, though not many. I also had some pretty bad steaks in South America, which isn't surpprising. (I've also had really bad French food in France, but I swear I couldn't find bad Italian food in Italy if I tried. Go figure.)
That said, I don't usually order the non-US beef at TS, 'cause I prefer US beef. I know that they used Canadian grass fed at some point in the past, but I am not sure what they use now. It is possible that the grass fed beef used now comes from somewhere much closer to Montevideo than Montreal. Next time I stop by for chorizo, mollejas and alfajores, I will ask pointedly.
People don't get much more Porteno than the crusty butcher and his sidekicks at El Mercado. I think that the chorizo and morcilla (and also the chimichurri) is genius. The empanadas, too.
UPDATED: The TS menu's specials section includes a list of steaks under the heading "Fine Argentine Range Grown Beef." Now, I'm not sure how many ways that language can be parsed. I suppose it is possible that some beef is "range grown" in Argentina then finished in Uruguay or Brazil (before the recent Brazilian foot and mouth outbreak, leading to bans). If the Argentine beef ban is still in effect here, I guess I don't see how TS can make the claim. I have no doubt that Uruguayan beef is indistinguishable, and maybe they figure that Americans don't know from Uruguay, but still. And if the beef is from Canada, well, the statement seems to be misleading at best. (In his defense, the butcher speaks no English that I can tell. Spanish or Italian work.)
PPS, in looking this stuff up (Beef-mag.com is a good source, though the title is confusing) I see that South American producers are now moving toward grain-finishing, to reduce the "negative impact" of "forage-finishing" (which I take it is a pejorative way of saying 100% grass-fed). Taste-wise, it's apples and oranges for me. Chewy, grassy beef can be tasty when properly butchered (the SA cuts account for the firmer grain) and cooked, and it is much better for you. But count me in for a big, buttery slab from Morton's (or Matsumoto?).
The environmental angle eludes me. While feed-lot finishing must be very unpleasant for the cattle, I can't help but doubt seriously that 100% "free range" cattle production is good for the environment. Brazil's need for grassy open spaces is directly related to deforestation, eg. (Brazil is the world's #1 beef exported, by far, BTW.) More cattle, at their largest, trampling and dropping waste onto more open land, for more days, seems to be a sum negative compared to growing more corn in a relatively microscopic space then feeding it to the cattle.