The bottom of the report includes the following:

    Module                Need  Have    
    --------------------- ----- --------
    Cwd                   0     3.74    
    ExtUtils::MakeMaker   6.36  7.35_03 
    File::Find            0     1.29    
    File::Slurp           0     9999.19 
    File::Spec::Functions 0     3.74    
    Test::Compile         0     v1.3.0  
    Test::More            0     1.302137
    UNIVERSAL::require    0     0.18    
    URI::Escape           0     3.31
[download]

So they do have File::Slurp installed. Unless you're seeing this same error with a lot of testers, it might have just been a one-off problem on that particular person's computer, like a corrupt hard drive or something.