How to maintain Chrome "enable request blocking" after closing dev tools?
Unfortunately not the solution. However my workaround for that is to have the dev-tools as a separated window either minimised or just in the background if i don't need or want them.
Opened up a chrome ticket to add this. If you think this would be a useful feature, then voting there will help get it on the radar. https://bugs.chromium.org/p/chromium/issues/detail?id=1269320