-it doesn't understand context
-if the spammer uses related words, good luck catching those
-false positives can be quite high
As a recruiter receiving such a wonderful automated reply from you, I would ask you why didn't you use a more suited technique to the problem such as transformer-based attention network, or at least deep learning neural network.
If he fixes the polish bug and grabbed more training emails from friends it would be even better than 95%. Which is why Bayes works well enough http://paulgraham.com/better.html
It's pretty clear he wanted something cheap and fast to implement and the headaches of getting a neutral net working aren't part of that formula. Honestly seeing how he cobbled together a lot of separate parts into something that works is pretty damn impressive and is exactly the type of thing that would fast track him if I was interviewing him