You know, sometimes Twitter is not the tool you'd like to use.
Swallow your pride and just do it! Reach out to them on the friggin Steam forums if you have to, that's where most of the indie dev scum hangs out. Hell, only today did I realise that the company behind Slender has an actual community manager by the name of "Community Manager - Denis" that still regularly posts on the Steam forums. So maybe you guys - or some committed goglodyte; I'm looking at you tfishell, I know you have a Steam account! ;P - can reach out to him in a last-ditch attempt to get that latest build here. At least then you'll have exhausted all the possible avenues. It may not look professional, but you owe it to your customers to try everything to give them the best possible product.
Also, the fact that Cinemaware isn't being pulled seems to imply you're still in contact with the rights holders. Then why has the Cinemaware Anthology (that includes all the stuff that gog is selling for $17.97 and much, MUCH more for $9.99) not been released yet? What about that "way they're going to make it up to their customers" - back in 2014? Any word on that?