Python is not used by SAMSON, Python is present in the launching script just to add a path to its libraries so that users could use the Python Scripting Element. So you can safely comment the Python-related block in the launching script if you are not using the Python Scripting Element.
The information you see in the About dialogue (or in Preferences > Installation > General) shows all the graphics cards, meaning that it can show both CPU and GPU. But in your case, the SAMSON installer could not find your Nvidia GPU.
Personally, I used SAMSON before on a laptop with Linux (Ubuntu) equipped with Nvidia GeForge GTX 670MX GPU (which has Optimus technology) but without Bumblebee/optirun installed. So the problem seems to be either in SAMSON not being able to properly detect GPU or lack of some drivers.
How did you install SAMSON? With optirun or without? Does it give you the same behavior in both cases?