If a politician spouts outright lies (to the effect of "this next bill will do X, Y, and Z" a few days before the bill is signed, when it does none of those things, which is akin to what happened here), they justifiably will get a ton of complaints from people.

When you put yourself out there in a public space, and especially when you're charging people money, you risk major backlash if you're caught lying about significant things. Does that warrant death threats? Of course not. Does it warrant criticism, protests, demands for refunds, and accusations of fraud on social media? Definitely.

If the game dev considers public backlash harassment, he should enter a new line of work and/or not lie to paying customers. Except for cases where the harassment turns into threats, he has no right to complain. He's the only one who put himself in this mess.