I didn’t mention the name of the spambot just in case they have some kind of keyword monitor that they’re using to monitor and circumvent potential spam filtering tools.
That being said, the tool is using a tesseract-related wrapper, and it might be having trouble picking up the text.
Also, another thing I noticed about the code is that it only activates if it detects 4 or more words in the image. Did the image you post include 4 or more words?