No, Rav Shteinman was never in favor of any such thing as chareidim serving in the Israeli army, despite any blog reports that spread that falsehood. Any he bears no responsibility for the creation of the so-called Nachal Chareidi, which is 80% non-Chareidi.
Recently Released Letter By Maran HaRav SHteinman To Hagon HaRav Don Segal Regarding Nachal Charedi
Maran R’ Shteinman Tells Yeshiva Student To ‘Go To India’ Instead Of IDF
http://www.theyeshivaworld.com/coffeeroom/topic/rav-aaron-leib-shteinman-opposes-nachal-chareidi