Only thing I'm nervous about is that they are coming from Malaysia, and I read some people don't trust ebay users from there. I don't even know if these are the users pictures or just copypasta
I've sold a couple of pairs of these to buyers in Malaysia, so I know that there are genuine Oakley Grenades in Malaysia. I've also never had any problems selling to buyers from Malaysia. I know there is a lot of anti-Malaysian sentiment from sellers but from my experience I can't understand why.
However, the amount of fake Frogskins on eBay right now from sellers in Malaysia is alarming. If you're not comfortable you can just cancel your bid. Alternatively ask him to take some specific photos (close up of the tag/barcode on the box, lens etching, other giveaways of fake Frogskins, or anything really just to see exactly what he's selling and see if they match the photos he's using in the listing). Any good seller should oblige. If he can't, I'd back out.
The only way I know of telling they are real is seeing the bar code on the box, I notice they didn't post a pic of it. That's why I'm guessing they're fake, also I saw how good the fakes are in Malaysia