It is likely that the #80 mesh is not easy to make a stator by hand, which leads to the failure of the omega driver, and the driver housing made by resin at that time was not as strong as later 007 009 though. There are some DIY estats such as Perun and Phenomenon in Russia, they use much lower number size copper mesh as stator. I have owned a pair of perun, the stators are made of about #10 copper mesh, the mesh itself is very strong actually, and is glued to the PCB holder with structural adhesive.
As for the glass stator of the HE90, the glass is indeed rigid, However, as a stator, it does not play the role in the Sennheiser advertisement at all. The only thing I can expect is that the glass is chemically stable and not easy to be corroded or oxidized, and Manufacturing microporous glass plate is extremely expensive which also leads to the insane price of the HE90... Unfortunately, Sennheiser is now not planning to stop, they use even more expensive ceramic based PCB stator on HE1.😦