Taking criticism, as constructive as it may be, is tough. It's often said that it requires a certain level of maturity to take criticism. Sure, the internet is full of people that just want to push buttons and piss you off. It's also full of great advice from people that genuinely want to see you succeed.
If you see a developer responding with hostility to a simple comment, you can bet they do the same with coworkers. While they don't exactly have to give in to the demands of investors, being able to listen and just consider their ideas is a good trait. A developer that responds in a friendly way, thanking you for your input, is one you can be confident in.