If you ask anyone why the other µ’s member stepped back, I don’t think anyone would have an answer for that.
If you’re seeing this romantically, or as something special, then it is a strong subtext. It is implied that it can be a strong subtext, but it doesn’t necessarily be one.
As for why the private moment, I believe it’s just the theme that Kimino picked/decided to go with. You can say the same for the NozoPana and NozoHono that most people already seen (and NozoHono is more misleadingly yuri-tier in context)
Special relationships in anime/manga between Rin and Nozomi are not apparent enough. They’re more apparent on audio drama where both of them are actually close and always play the tsukkomi-boke roles, aka making puns. So if you ask me, they’re actually quite close. The only question now, which LL-verse does that audio drama belong to.
To be fair though, all these pairing business are more of something that has yet to be developed. If there’s one pairing that suddenly pops out and it’s an odd pairing, see it as something that has yet to be developed. That is however, depends on how deep the context be (As how popular it is, it’ll depends on how many people would hype the pairing, really.)
One thing that should be remembered all the time, SID doesn’t necessarily make story based on pairing, rather than, it revolves around character development, and this one is just a tiny clip of it.
This one chapter doesn’t breathe much yuri. It didn’t reach that high enough to be one. Being paired together for private moment alone is not good enough. P 16/18/20/23 may implies those, but, it’s more of a “Good friend” relationship and “On spur of moment admiration – P.23” rather than yuri. It may become a good material in the future, but as for now, I don’t see anything that stimulates that yuri-excitement.
Speaking of yuri implication, the game (especially those side stories and Ch 27 valentine) and audio drama reeks of yuri more than anything. Dengeki G’s issues are baits of baits.
If OT9 doesn’t work in your eyes, then it’s just the way it is. Everyone has their own preference, right?