httpstat returns 403, doesn't hide timings

I built the project by downloading the git and running "go build" instead of the supplied command because I got an error

can't load package: package github.com/davecheney/httpstat@latest: can only use path@version syntax with 'go get'

When I use the following command: ./httpstat -I -L https://pieterhouwen.info I get the following output:

When I use curl on the same website it works fine.

What is the reason for this 403 and wasn't the -I parameter supposed to hide the timings?