Presumably this is to prevent naming collision with the existing Tesseract, an OCR engine. Its generally worth searching "my new awesome name" "software" prior to picking a name.
Agreed, the first time I read about Tesseract/Crossfilter on HN a couple weeks ago I clicked the link thinking it was a new version of the OCR. Just to find out it was a completely unrelated project.
Well, it didn't hurt the project much to ship it first and worry about the name later. Also I remember reading somewhere that one of the creators was aware of the OCR engine but didn't anticipate it being a problem. So googling wouldn't have helped.