It's really no different than physical exercise. Yes, it can be painful in the short term, but over time it allows adaptation that increases strength and robustness.
Jl is probably aware that this sensitivity can be overcome, and how to do so. Sometimes it's ok to pass over a thing in silence instead of telling a stranger to smile.
That's not how I interpreted Pacabel's response. I interpreted it more like him/her telling jl that his expectations of Daniel 'fixing' HN to ban critiques are unrealistic.
(I felt slightly bad about my response, in retrospect; I meant "YC partners seem to be subject to particularly harsh criticism, which is unfair. Perhaps if you were anonymous it would be less aggressive trolling directed at you." I'm sure jl has thought of that of course.)