I would suggest that you stay away from link partners who employ questionable tactics, not by inches but by several miles.
The first simple question that you should ask yourself is why they have to use such as the weird character like @ in their file name...Perhaps their intention is to prohibit spider to crawl link pages.
To answer your specific question by yourself, you may want to look at Google cache to determine whether the page is crawable. If there is no cache, you better say "NO" also.
Another important point is that:- Don't be deceived that the site is of good quality because the main page has PR5. The danger zone here is that if the webmasters intentionally hoard PR by prohibiting spider to crawl other links, they also have a bad habit of linking out solely of their own sites. As a result, link out is in a closed loop within its own network and it can be a perfect condition for G to detect that.
So here is the TIP. Whenever I encounter this instance of link page PR0 and homepage PR4+, I will also look at the cache of the homepage. If no cache for homepage (although PR is shown), you can assume the site suffers penalty. If that is the case, would you still be interested to exchange link?