Well, I suppose we could get into a debate on the meaning of the word "mechanical". It could be argued that rubber dome boards are mechanical as well, and the touch screen or roll up membrane boards are the only non-mechanical boards. I really don't want to have that debate, but if backed into a corner I could make a case.
Anyway, without taking apart the board and seeing the way the "switch" makes contact with leads or a membrane, I can't really argue by the definition for "mechanical" most widely accepted here. I also have no plans to disassemble this board to check any time soon.