Right. Well the issue here is that the phototile gallery is intended for more pictures, kinda like the example in the screenshots of the plugin. For a post like that one where you're only going to be displaying 4 photos, I'd probably just insert the photos into your post by single images instead, using the "left" alignment option which would float them together.
The only thing that I can think to solve this type of issue might be for it to count how many photos were returned by the RSS, and if they were less than a certain amount, have it select the template layout based on the number of photos rather than randomly.
I'll consider options to perhaps correct this issue.