I’m just going to answer the OP without going through the other posters (I mention this in case my response reflects a message I wouldn’t want to make, in light of previous responses), as a Lubavitcher:
It’s sort of the difference between “Lekatchila” and “Bedieved”. To begin with, the entire tnua was anti-Torah (……), but once there is already a state, it hardly helps to fight against it, and so the stance is preserve and nurture that which accommodates true Torah values.
To emphasize: even today, Chabad’s stance is NOT to embrace the said tnua of Zionism. Rather, as it stated, the stance is to embrace that which adheres to Torah, notwithstanding Zionism in its anti-Torah image.
This is similar to Chabad’s stance towards Reform Jews/Judaism. Towards the tnua, no recognition whatsoever. Towards the Jews– we treat them as any Jew.