Telling developers that 100% test coverage is an anti-pattern is like telling a room full americans that running too much is harmful to your health: true, but not helpful.
The reply was great; it acknowledged the value of test coverage metrics while also understanding the dangers of using it as a numeric goal in the extreme. True, and helpful.
To put it another way, saying "50% test coverage is fine, sheesh" should encourage more testing, because it lowers the bar you have to strive for to consider yourself to be "doing it right", and therefore makes it easier to talk yourself into trying at all.
It is a subtle, but extremely important, distinction.
Granted, too little testing is probably the more common error.