The "don't break his balls over a few bucks" could also applied the other way around. A free steam key for early supporters (like other devs here do) would gain a lot of respect or a discount would be reasonable but getting nothing for supporting early is just disrepectful. Its also bad long term for him, people are going to think twice about supporting early when he releases new projects.
if he gives out keys, lots of them are just gonna get re sold on key sites, and steam puts limits on how many keys devs can give out anyways. also its not typical to expect a key for a different platform when you bought it on itch. itch isn't like kickstarter. when buying a game you almost always only get the game on the platform you bought it for