Just some quick calculations based on what he's advertising, I totaled just over $15K worth of tools at todays prices. Assuming he's bought them over the last 3 or 4 years, I reduced his costs to about $13.5K by taking out Festool price increases. If anything is used, that number further erodes away. So, basically he's asking for 90% of what he may have paid if they were all new.
Based on what he has and the pictures, I would not expect to find that anything is stolen. It's clearly someone that had an extensive hobby shop and kept it somewhat portable based on the MFT benches he made for storing all the systainers.
I would agree that he's not likely to find someone to buy the whole thing at only 10% off what he paid and even at 20% off todays price is a bit steep unless someone is starting from scratch and has quite a bit of disposable income available. Obviously, if he's moving and can't take it with him, it's going to interesting to see how this unfolds. I wish him luck.