Yeah but think about it - imagine government employees shift their entire focus onto "securing US networks". What would they do, exactly? Build their own open-source chip designs from scratch? Because that's pretty much step one.
Do more work like SELinux.
There's lots they can do.
Step two would be to consider some shared infrastructure, probably subcontracting with a cloud provider (AWS/Azure/GCP), hopefully multiple. Once we get to that step, then you can start considering things like Google's Titan (https://cloudplatform.googleblog.com/2017/08/Titan-in-depth-...). But there's a lot of low hanging fruit before we get there.