It's not freebooting, it's more akin to hotlinking. Which is arguably worse - they're using the author's IP and hosting infrastructure without offering sufficient credit or so much as a heads-up.
This could quickly make a side project unsustainable, if the owner of a (hypothetical, not this specific) project has limited $ for hosting costs. The author of the project can't make use of the obvious strategy of dropping in an ad or two to defray hosting costs because the images are being hotlinked. This kind of behavior would be a violation of the ToS on almost any site that has one; it would certainly be a violation of Apple's own ToS. But beyond that, it's just thoughtless and rude.
Hotlink sounds a lot like hyperlink. Really it just sounds like people need to protect their content with licenses and "website experiences" with terms if they want to enforce restrictions on how things they host publicly are used. I agree it seems rude that they didnt give the owner any warning, but meh.
This could quickly make a side project unsustainable, if the owner of a (hypothetical, not this specific) project has limited $ for hosting costs. The author of the project can't make use of the obvious strategy of dropping in an ad or two to defray hosting costs because the images are being hotlinked. This kind of behavior would be a violation of the ToS on almost any site that has one; it would certainly be a violation of Apple's own ToS. But beyond that, it's just thoughtless and rude.