But wouldn't density make things worse? Helium can be used for noise attenuation like this because it's light, so you get worse acoustic impedance matching between the panels and the gas. Argon is denser than air.

Helium would leak out fairly rapidly, no?

I can see the benefit of impedance mismatching but i truly think that for an application like this it cannot be worth the effort until you add in the "marketing" intangibles.

Why not fill the panels with water? gloinggg

edit: IIRC argon filled double pane windows are a thing partly because the argon doesn't absorb moisture like air does; so there's less chance of condensation happening in between the panes. So perhaps they just bought double pane panel that were commercially available and ran with the sales brochure from that to fill out a press release.