Feeling obligated to appease unseen internet freeloaders.
If you do it because you want it for your stuff, cool.
If you do it because you feel obliged to appease "the community" who takes for granted that you support them, that's a symptom of the broken model that is open source.
Has echos of the Linux for Apple Silicon guy last week who used to be a Wii modder, tired of the support tickets from entitled pirates, moved to a niche Linux distro, and discovered a similar sense of entitlement in the issue tracker.
In general, nothing, but it made me a bit sad that the maintainer believed he "owed" the community (likely 99% full of people who were using his work for free) to the point that he spent money for someone else to do work that he couldn't find time to do himself. Instead of just shuttering the project earlier, and saving that money.
I really hope the "significant sum" he paid was out of donations to the project, and not his own money. Even then, it sounds like he's poured a ton of his time and energy into the project over the years, so even if it was all donated money, he certainly could have kept it for himself without any moral/ethical concerns.