First, Herzl didn't start Zionism. It was around way before him. His ideas were not original, and pretty much everything he had to say was already said by Zionists before him. Most of the ideas in Der Judenstaat about the causes of anti-semitism and his fantasies about how Zionism will end it were already printed by Leo Pinsker in Autoemancipation. And Moses Hess came up with the idea of Zionism before both of them. There were many Zionists before Herzl. The first Zionist, though, was the heretic Benedict Spinoza, as the main idea of Zionism is that the Jewish people are a nation like the Italians and French, as opposed to the Am Hashem. Spinoza invented that idea. Herzl's contribution to the making of Zionism was not that he thought of it first, but that he managed to make it into reality through his political and organizational activities.
He was no tinok shenishba. Although he had no Jewish education, He was well aware of Judaism and much interaction with religious Jews about it. He knew the Chief Rabbi of Vienna, Morris Guderman, and even consulted with him about Zionism and related topics (Rabbi Guderman told him Zionism is against the Torah. He did not care). Tinok shenishba applies to a person who did not have the choice of becoming frum due to his lack of knowledge that being frum is an option. Herzl was not in that category.
But besides that, Herzl was a terrible frumophobe. His views were strongly influenced by anti-Semites and he hated frum Jews with a frightful passion. Some of the things he said and wrote about them sounds like it could come from someone like Joseph Goebbels. I am not kidding. Herzl hated Judaism and frum Jews and expressed his hatred with stereotyping and mockery - just like the gentile anti-Semites. The Chazon Ish said about Herzl that there is no problem applying to him the statement yemach shemo. We do not use such curses on innocent people.Herzl was not innocent.