OK, so this woman was approached by SG HR because someone had given her name to them as someone AS may have been a bit handsy with. That sounds off to begin with... the "whistle-blower" had no right to do that, and HR had no right to contact her, surely? It's for the "victim" to come forward with any complaints of their own free will, I'd have thought. Not for them to be fished... Other than maybe sending out a generic, all-staff message to say our guidance on this has changed so you can now make a formal complaint about some things that you may have been told that you couldn't before.
She was concerned that there was an "investigation" she could "impede" if she didn't lodge a formal complaint - how did she know, and why would she care? If she didn't want to complain that's the end of the story, surely? She shouldn't be worried that her failing to disclose very personal and potentially triggering facts to her employer was somehow inconvenient for her employer.
So she went to LL to check (her line manager, or mentor or something possibly, but would seem a strange choice to pick her at random as someone she "respected") but didn't mention any names or dates or what it was about, and LL knew exactly who to go to?
. And nothing went any further.
But somehow a couple of years later she's watching the telly and sees DD doing his stuff, and assumes, "oh, that must be that thing that I didn't want to take any further that LL was accused of "interfering" about. Better contact Rape Crisis and tell them what happened". Sounds very odd to me.