Immaterial of the Ferguson/RDA fight and whether RDA would have won if it weren't for the eyepoke, something we'll never know, this...
The fight took place in November 2016. That's post-Jon Jones. New ABC-unified rules had already been passed turning reaching toward your opponent's face with an open hand into a foul. Nobody competing in MMA in 2016 did not know that when you paw toward your opponent's face with an open hand, he's probably going to get gouged in the eye. The most generous realistic interpretation is that he was deliberately using a technique that he knew would probably result in an eye-gouge, but saw that as an added bonus rather than his primary intent.
And you know what? I don't even blame him. When eye-gouging is not penalized and fighters make twice as much money for winning, how can you? I'd poke Dos Anjos in the eyes too if it might be the difference in whether or not my daughter gets to go to the best university that accepts her. Don't hate the player, hate the regulators who incentivize this shit. But let's not be naive. The pawing motions to find range happen all the time because they result in eye gouges and aren't penalized, not despite it.