An interesting argument, but also one with a very severe and glaring flaw. That speech was in January 1860. In between then and December when secession started, the Republican Party formally adopted protectionism as a central platform plank and nominated a well known protectionist as their presidential candidate. Therefore, while it is true that in January 1860 the Republican Party did not subscribe to protectionism, that changed in the summer when they enthusiastically endorsed it as a central plank.
Lincoln was nominated because he was a moderate. No one gave a fig about tariffs; that's a smoke screen adopted by apologists in order to hold the slave power blameless.
Walt