I reread Nightwing/Huntress earlier this summer, and I don't recognize Dick's motivation in your description. The story contains a lot more discussion of how Dick resembles Bruce, at least more than he'd like to.
I think Dick is attracted to Helena briefly for the same reason he's attracted to Koriand'r and Barbara Gordon: they're all strong women who also come across as vulnerable and in need of a rescuer. (See also Miggsy in the first Nightwing miniseries.)
On Helena's side, at the end of Nightwing/Huntress she acknowledges that she enticed Dick into bed in an attempt to get closer to the bat-clan. What's most interesting in the long run is that, even though in the panels above Helena insists Dick and Barbara weren't together yet, she saw the sexual attraction between them before they could acknowledge it themselves.