Its not the code so much as the model. The model itself can be poison pilled and embedded with ideas that make it unfit for use and there isn't a person out there who can look at the weights and tell you what or where the problem is by looking at the code.

this isn't if-else statements, its a jumble of linear algebra and matrices.

I watched a demonstration where one AI was trained to be obsessed with penguins. they asked for a random set of numbers from it. They fed that set into another AI model to analyze and the new model started to become obsessed with penguins.

I dont think open source is the only one to worry about though. I don't know if we even have a way to guarantee any model is secure, open or closed.