yes it is.
Looks extreme. if you are so worried lookup blocking things via editing your /etc/sysconfig/iptables file (there are links on here with lists)
Less radical. can be reversed. does the job in the main.
Also a "gentle" log nerf might not hurt
(redirecting the output to > /dev/null say)
one might disable OTA updates
Hope that helps. They are all fairly low risk assuming you do them correctly.
Don't brick your device - it's not required.
The enormous DO NOT DO THIS really should be warning enough.