They aren't all available. I have brought this up internally and still no definitive response, but I do know that some materials are being migrated, so itt you are getting a redirect to GeoNet, that might be a good sign. If you have particular requests can you provide a text version of the url.
Flagging Timothy Hales I brought this up on Moderators, with no response as yet and only 4 view from the Mods. Could you forward to the migration team since there have been a number of requests and old forum posts are indeed going to GeoNet's void
It would be a tragedy that is not available anymore, I was consulting it until late last year.
This time I wanted to see topics about creating bar charts using ArcObjects with data tables of a feature class.