Emerson is not exactly dumb. He can talk to machines and can intuit how to build new ones from conversations with them. He tried to crack AI and he got ZARI, but ZARI's only works because of their special bond with Emerson. When he tried to make other ZARIs they were all really stupid and would often flip out. But Emerson's emotional intelligence with machines is where he shines best.

Emerson has always felt insecure that he wasn't as conventionally knowledgeable as some of his peers. So he would often do things to make himself seem "smarter". And it worked for a lot of people. But it was hard to maintain and he was always afraid of slipping. Constantly worried about how long he had to wear the mask.

It's those kinds of worries that prevented him from seeing any of this coming.