No one 'deserves' anything, but it's worth noting that it's not impossible to create fast-moving and nurturing environments, and maybe trying to learn how to do that for your peers.
"Deserve" means to show qualities that are worthy of either reward or punishment.
This poster is someone who took the initiative to get better and therefore showed qualities worthy of reward. They absolutely deserve better than they got.
How can you be so sure? You don't know what the compensation of the GP was, you don't know that they weren't / won't be written a stellar letter of recommendation (or better yet introductions) that will land them directly into coveted senior dev land, you don't know that the experience forged won't make the GP an effective startup founder, etc, etc etc.
