Assuming Woo will need waivers to be sent back down......does he likely clear, or would some other team take a flyer on him?
Unless he comes to camp and absolutely blows expectations away, i don't think you can afford to keep a player like that on the roster just because you're afraid of waiver claims. He's not a really special player. There will be dozens of same or better defencemen on waivers around that time. Pretty much every team has a fringe guy like Woo on the cusp, that they'll be trying to slip down through waivers because they also don't have room for them.
Yes, it's a risk that he gets claimed...but if you're serious about competing, you can't be so lost in the minutia of "asset management" that you keep inferior players around. It's really not even a productive thing, to keep a still developing player like Woo around as an 8th D who spends all his time in the press box. He needs to continue to play and get minutes if he's going to be anything.
It's unfortunate that we haven't even really had a look at Woo at the NHL level before he hits waivers...but that's just the nature of slower developing prospects.
You ultimately just have to run with the idea that if he's not good enough for our defence, he's not going to be good enough for other teams either...and they're all dealing with their own little projects that they want to keep. Sometimes it ends up like Gadjovich...but more often, they just get lost in the shuffle and nobody even looks twice at them.
If you do lose him...that sucks, but you can probably find a replacement on the waiver wire who is just as good, if you need one. He's not a guy with huge "upside" even if he "hits" at the NHL level. Like...realistically, Juulsen is a better, more proven player at this point...and he's cleared waivers how many times now?