The "unreal" PageRank, although perhaps a fleeting, temporary assignment, may still have significance. Google's crawl is queued by PageRank. If it discovers a page for the first time on a crawl (i.e., the page has no inbound links and is only linked from your higher-level page, meaning that it's "discovered" anew on every crawl), then this temporary, "fake" PR value may determine where it's placed in the current crawling queue.
Why is this important? Well, if your site is small, it may not be important. If it's large, it could be a major factor in determining whether Google gets to that page before the crawl is over.
If there are no incoming links, it's also possible (don't know for sure, but it seems reasonable), that the "fake" PR value could play a role in the ranking. I don't have any evidence one way or the other on this.
Why am I making this point? Well, lots and lots of internal pages on a site don't have inbound links from other sites. It would be nice to figure out how Google treats these pages. Most other sites link only to your home page. Most Google referrals go right to an internal page. The difference between these two is a measure of why this issue is significant.