Got it, and thanks for your diligence in checking the rules and asking for a second set of eyes.
I think the main thing you’ll want to consider is whether your service might be posting significantly duplicative content, along with overuse of hashtags or mentions, which may lead to antispam algorithms being applied.
It looks like this is enabling unique image-based content sharing, which is not directly prohibited or problematic. We’re unable to provide absolutely specific guidance since our algorithms are tuned via a variety of signals and machine learning, but if this is more-or-less a clearly marketed, opt-in Tweet scheduler for image-oriented or themed content, and not misused for spammy URL, hashtag or mention posting, then I would not anticipate significant problems.
