I don't see how losing on purpose is unsportsmanship.
The format gives you a chance to experiment and if you are confident that it will help you maximise your chances to go further in the tournament, I don't see the issue with it.
I believe there's a lot of difference between "experiment" & "intentionally losing to avoid harder match-ups". For example, Viper so far is experimenting often with Portuguese. While many thinks he's trolling, he said he legit thinks Port is good. Even when he picked Port, he played to win.
While on the other hand, if he intentionally lose (no way to tell tbh) to get to the lower bracket instead, that is completely different and what I considered unsportsmanship. It's also a matter of respecting your opponents and the tournament organizer too.
To me, sportsmanship doesn't mean you always have to go meta, optimal strategy etc. You can go for weird & surprise strategies, but what I expect from players in tournaments is that even if they go for sub-optimal strategies, they play to win. Instead of play to lose on purpose and take advantage of the format and existing circumstances of other group's results.
Maybe from your other favourite sports, losing on purpose to take advantage of the group format is always part of the game and not a problem to you, and I think we can keep our differences.
Losing on purpose will always be unsportsmanship to me. If you wanna win a tournament, do it by play to win in every series, not with the help from intentionally losing.