Board Thread:Manga/@comment-5774380-20160408232143/@comment-26932251-20160427102112

Crazy thought, the series has at no point confirmed or denied that Eren's titan control ability can't be used on titan shifters' titan forms.

At some point in the series there is mention that a coordinate holder who is experienced in its powers has something resembling 'invincibility' and that Frieda Reiss could only by Grisha because she was unable to utilize this power.

Objectively speaking, if Eren could control the Homelanders' titan forms, then game set match.