This is the article in question. Key paragraphs:
Once upon a time, one could hop aboard a train in downtown Cairo and within a few hours be in Jaffa, Beirut or even Damascus. Journeys by car or lorry were similarly commonplace. Unfortunately, normal land travel between the African and Asian land masses was all but halted by the creation in 1948 of Israel, which stretches from the Mediterranean to the Red Sea.....This blocked Egyptian industry off from cheap cargo routes to crucial regional markets, including those of the wealthy Arabian Gulf. Egyptian products from then on had to be expensively unloaded from cars and lorries at port and placed on ships.
The article means to argue for the need of the proposed Saudi Arabia-Egyptian bridge across the Straight of Aqaba/Red Sea.
Color me extremely skeptical. It's a counterfactual obviously so we don't know but we might well compare Egypt with countries that were not "blocked" off from those land routes like Syria, where we would find that Egypt is comparable in terms of GDP per capita. Perhaps more strikingly we could compare Egypt with the country that has been more "blocked" off than any other in the region, namely, Israel itself, and find that the Israeli economy has purred along just fine.
I also find it to be unlikely that even absent the creation of Israel that you would have significant land shipping routes from Egypt to the GCC given the distances and terrain involved. Also while Egyptian goods might theoretically be purchased within those markets (and, indeed, they are as evidenced by the Egyptian potatoes I passed by in a Dubai supermarket this evening), the only thing they would plausibly be selling back would be oil. Egypt imports and refines quite a lot of oil, but I'm not aware of anyone making the argument that transport costs of that oil from the GCC to Egypt have dented Egypt's economy.