The consensus amongst the majority of gdolei yisrael before and after the War , was clearly that Zionism is bad.
Bad , does not necessarily mean heresy.
So both sides on this thread are wrong.
Its not heresy, but it is bad.
It is not a choice between heresy on one side and “good / part of thora” on the other side.
It is a choice between
1] heresy
2] good and part of thora
3] not heresy but wrong and obviuosly no part of the thora.