Thats not the only argument against inline images:

4.4.3 Why doesn’t text/gemini support inline images?

This is a deliberate decision made in direct service of the guiding principle of user autonomy (see answer 4.2.2), specifically the idea that text/gemini documents should have no way to trigger additional network requests. Images are one particular case where this principle also overlaps substantially with our guiding principle of user privacy (see answer 4.2.1). So-called “tracking-pixels” have been a standard tool of the internet’s surveillance marketing complex for many years. These tiny, invisible images abuse the web’s behaviour of automatically downloading image files from arbitrary third-party servers to effectively trick your computer into “pinging” surveillance servers, reporting your movements as you explore the web.

gemini://geminiprotocol.net/docs/faq-section-4.gmi