He really shouldn't ignore customer PMs but he does get a ton of business since he was the only trusted U.S. based hardmodder until vb_encryption_vb, and he's also the first modder in the picture gallery for the hardmodder list.
People are upset because after waiting several months for their units with no feedback, they have no way of knowing if their unit is gone forever. I understand that he has a lot of business, but he either needs to be upfront about the ETA on repairs and not dissapear from forums for months without contact, or have a waitlist for customers when he's overwhelmed instead of taking their units and money upfront.