I am not exactly set on that orcs are Turks but there is certainly a West biased West vs East theme in his books and maybe it is not directed to only one race but there are a lot of things in these books indicating he was at least having some prejudices towards general people of the East. Claiming that this is non-existant, imho, is willfully overlooking and finding excuses because there can only be so much coincedences.
One other thing I want to mention to you, because I enjoyed this conversation with you, is the name Turk is coming from ancient Turkish word Toruk. Toruk means the one who follows the customs. Turks are nomadic barbarians from middle Asia who migrated to Middleeast and got heavily mixed with Persians and Arabs. They got taller and bulkier. Toruk sound like Uruk. :) Btw I am Turkish and I don't really mind and not it's might be a coincidence too. So not really sure about this connection. Added it as an interesting tidbit.