R2 specifically. I chose R2 on account of the pricing model that charges only for storage and not data egress (bandwidth). That's actually a fairly big deal because with other options (e.g. S3) you're always at risk of getting a huge surprise bill if some hosted data gets really popular, and this forces all the services built on it to host third-party data to be post-pay with no guarantees to the customer about how much they will be charged.

By replicating R2's pricing structure, Satellite CDN is able to be flat-rate pre-pay, and therefore a good fit for lightning.

If you're concerned about censorship, that's what NIP-94 is for. For every file uploaded, Satellite essentially creates a torrent for it, and returns these params to the client. So if Cloudflare ever pulls the plug there will, in principle, be recourse to self hosting. Also, the url path of every file on the CDN is just the SHA256 hash, so to deal with the problem of dead links in the long term, clients could just parse out the hash from dead links and serve the same data from a different host.