Salted Turtle

I know this is old but I just read the book and I think he still might be a rithmatist. We know that in order for their drawings to activate they have to will it. He actively didn't believe it would work. He saw the thing only rithmatists see and I think he lacks faith or belief in himself to actually make it work. Or it could be a bigger thing that will come up in second book. Or I'm just wrong.