While there ARE some inexpensive products out there that work the trick is to know what is cheap but good vs cheap and bad. For that sort of decision I pretty much rely on reading reviews of the stuff and then reading between the lines of what is said by the reviewers. It's still a gamble but at least you can go into the purchase with a bit more of a feeling.

For some reason the link didn't want to open for me until just now. From the looks of the picture I'd say this is a basic cup and cone hub and any seals are likely just rubber lipped guards on the shields that push in on either side. About all that can be said for it for certain is that it's a quick release style.

For a basic screw on freewheel hub and from looking at the others on the Niagra site I'd say that this is likely decent enough hub just based on the pricing of this one vs the others. And for the amount of riding you say that your friend will be doing it's likely that it'll do just fine. It's very likely going to be a better hub than the even cheaper ones shown. If it were me looking for a hub of this type for a vintage bike rebuild of some sort I'd likely go for them as well. Certainly compared to some of the other freewheel hubs shown on the Niagra web site this one has a much cleaner exterior look in the pictures vs the obvious machining marks on some others. And since USUALLY the inside quality matches the outside I'd say that gambling on two of these hubs would not be too risky.

Keep in mind that you still need to buy QR skewers for them.