I suspect that should she ever show up as Tim Drake’s aunt, keep in mind there are people whose own mothers (and grandmothers) dress skimpily. They’re not even unheard of (that’s if you study them more closely and either one of them could be a famous popstar). Though that would mean she’d not only replace both Lady Shiva and Dana Winters but also become much more involved in Tim’s life than the former, especially as his mentor.
That’s actually saying if because Dinah herself’s shown to be very motherly not only to Sin (her adopted daughter) but also a mentor to other characters on the Young Justice programme. If Tim Drake were her nephew she’d willingly take him under her wings. On the other hand, that’s pretty much realising there aren’t that many influential female characters in Robin stories other than Stephanie Brown.
Let alone one with a long history to boot. Dinah Lance as Tim Drake’s aunt would necessitate her not only replacing Dana Winters a lot but also becoming a big fixture in Tim’s life as she’s the one Tim turns to for support and learning. It wouldn’t matter what she dresses, some people’s mums do it too but that doesn’t make them any less parental. Though that would mean Dinah Lance’s a fully realised character.
And one who’d butt heads with Jack over Tim. (Though since she also has a flower business, she’d also help them along whenever they got broke.) So there’s that.