A hidden screen soliciting donations is certainly in poor taste when you're building a product meant to represent another entity, but "malware"? What is the attack surface on a conference badge that runs a Game Boy emulator?
And it’s software injected for financial gain, I can’t why anyone would take issue with calling it malware. A .txt file in the source folder of a game on steam stating “donate to the devs” with a crypto address is also malware. It doesn’t have to be sophisticated to fall under the category.
Also, a non-executable text file can’t be malware because the “ware” stands for software. That’s not malware, that might be social engineering.