It's a good idea; however, I assume that the loss incurred by the single save command from tif to jpg isn't going to be significant enough to affect the AI image.
Destructively throwing away image data is destructive, even if not perceptible at screen size. Folding a piece of paper in half is less destructive than crumpling it into a ball, but there is still a fold and that sheet has been altered.
Also, subsequent saves to JPEG re-compress the image, creating even more artifacts.
If Firefly is meant to be a fun toy to play around with AI and make fun graphics for, say, Instagram, that's fine. But if it's meant for professional-level, high-resolution images, it should support high-quality image formats.
FWIW, there are other threads in this forum asking for the retention of metadata. Saving from TIFF down to JPEG would lose much of that data.