I reckon fruit is fine in the context of a paleo non-processed diet.
Most fruits actually have a low glycemic load. Chimpanzees and Orangotangs eat a lot of fruit and they're usually less than 4% body fat. Apparently humans are more than 98% the same dna of these apes. (Not a hugely scientific argument I know)
When I passed through Dubai I went on a dune safari in a Toyota Landcruiser - basically just driving around crazy in the desert dunes. Our guide was this Emiratie guy who had a picture of his grandfather in his glove box.
The dude was totally ripped at 94 with all his lean muscle mass still intact - built like a 400 meter runner.
Apparently he just lived in the desert eating, camel meat, camel milk, goat meat and lots of raw dates.
Dates probably have the highest GI out of any fruit.