Moskva, at 600 feet long, was not a small ship. She was also not defenseless, with radar, SA-N-4 low-altitude surface-to-air missiles, and radar-directed AK-630 30-millimeter Gatling guns that should have offered a considerable amount of protection. That the ship intentionally sailed within range of the shore-based Neptune missiles suggests the Russian Navy thought it could defend itself.
A warship the size of Moskva should have shot down both Neptune missiles—this actually happened in 2016, when the guided-missile destroyer USS Mason shot down two ASCMs launched by Yemeni Houthi rebels. Moskva should have required more than two Neptune-type missiles to sink; in 1987, an Iraqi Exocet anti-ship missile, similar to Neptune, hit the frigate USS Stark and was saved by its crew. At just 4,000 tons, Stark was a third of the size of Moskva. There are numerous examples such as these that suggest Moskva should still be afloat, or at least have made it to Sevastopol.