I agree. I might also throw it in if they are acting like they are searching desperately for a seat, even if they don’t look like they need it. You never know.
I also don’t believe that giving a woman a seat does anything good for your chances to get with her in this situation. If she takes your seat, she’s likely going to turn away from you and face the bar, and sticking around trying to talk to her will be awkward with her back towards you. More often than not, she’s not going to turn back around, and you’ll just be out of a seat.
And that’s assuming some other person doesn’t take your seat before she has a chance. The only real reason to give up your seat is if you plan to actually go and talk to her rather than giving her your seat.