@p The ruling stratum was once instinctively opposed to life extension for various reasons. As it is a very difficult problem the lack of venture capital doomed even the attempt in the short term.

I've mentioned Drexler and nanotech recently. I've seen the culture shift 180 from when Engines of Creation was released. Now AI, nanotech and life extension are the primary goals of billionaires like Peter Thiel. If a viable path can be demonstrated the cash is going to flood in.

So if you want mankind to avoid developing it (assuming it can be developed at all) you need to become a fascist and ban it.