If we followed your reasoning, most CEOs would be immune from criticism.
I, on the other hand, have a different rule of thumb. If a company does something in public, it's fair game for the public to talk about it.
>You could use this logic to criticize basically any company expenditure as frivolous.
I hope not! That's not my intention. I'm just refuting the idea that branding requires a unique typeface.
The reason this is frivolous is because the company's core business is in writing the app and matching vacationers with short term rentals. Designing a typeface seems unrelated to their core business, and is probably best left to someone else, while they focus on what they're good at.