If by "back then", you mean 2010, then yeah.
But if you still mean that the specific term "wellness farm" COULD have been used as a euphemism for concentration camps (regardless of whether or not it ever was), then what's the point? Like people also COULD have used the term "suburb" as euphemism for a concentration camp. Should we also be skeptical of anyone who says they want to build suburbs? What's even the point of of saying that a term COULD have been used as euphemism historically?