Developers naturally has the freedom to choose where and on what they want to focus development time on, through I would not discount 32-bit machines as computers that should by now have died and be discared, especially in the server space which is what RMS is talking about during that 8-9m mark. A old 1U rack server is perfectly fine to operate as a router, a firewall, a logging server, a message bus, secondary backup (ie the server that simply get copies from the primary backup server) or some other low intensity work that is preferable done on a separate physical machine. If you work at a company that owned many of those you also have plenty of spares in case some essential old parts breaks down. You don't need a 256 core epic server with a 1TB of ram.

I suspect most kernel developers mostly operate with virtual machines in mind, but as a sysadmin I would argue that physical machines also has their use cases. I also suspect that if the linux kernel stop supporting 32-bit machines, others will continue. Are the BSD people thinking about dropping 32-bit support?