Answer: This is opinion because it is not evidence based. It ignores empirical evidence to the contrary and is not based on objective observation.
Explanation: From a physical perspective, we know that liquids evaporate from an open surface because random motion sometimes gives a molecule enough kinetic energy to overcome attractive force. This is somthing that we can readily observe. A puddle of water from river, sea, pond or lake in an impermeable container will dry up if the surface is exposed to the air.
The difference between fresh water and seawater is what is dissolved in it and if anything, it would be more difficult for seawater to evaporate.