"Jason and the Argonauts" is my all-time favorite Harryhausen movie, but it's a stretch to assume that's where Roddenberry got the name "Talos" from. As noted, it was a staple of Greek mythology that Roddenberry could have easily encountered at any point in his life prior to STAR TREK. Lord knows, I devoured books on mythology as a kid, and TOS is rife with mythological references and allusions: Who Mourns for Adonais, the Tantalus Field, the Venus drug, Medusans, etc.
Honestly, Roddenberry was more likely inspired by the real-life convention of naming planets, moons, and constellations after figures from mythology: Mercury, Venus, Mars, Jupiter, Phobos, Deimos, Orion, Casseiopia, etc.
Heck, "Vulcan" is a Roman god.