Nikki makes mention of some the conversations they had on board which seems to indicate there was some disagreements "We have had many conversations on-board about the climate emergency - about how bleak the situation is. There have been some heated discussions too - is it too late? Should we still hope? Can we feel positive? Is it constructive to be afraid? To name a few."
We're only speculating, of course, but I'd wonder if the disagreements might have been across generations. I remember being Greta's age and worrying about the Viet Nam War, the deaths of people of my generation, the environmental impact of Napalm and Agent Orange, the smog that regularly blanketed L.A., the fish kills that were washing up on the shores of the Great Lakes, and the fire that burned on the Cuyahoga River. I was convinced that the older generation had mismanaged things and the world looked doomed. I joined environmental groups and campaigns. I sometimes thought that God would be justified in wiping the human race off the face of the planet, leaving it to wildlife.
Fifty years later, I have the benefit of age and experience, to know that we survived, and that the human race continues to muddle along. I'm still concerned about the environment, and pollution, and I try to lead a life that, as much as possible, doesn't add horribly to the problem, and maybe adds to the solution a little. I'm glad for kids like Greta, and I applaud her effort. I don't see that her passion and concern does anything but good. She has found a platform that has other's of her generation thinking, and considering options. I'm more concerned about Kardashians, and kids of Jersey Shore, who seem more focused on fame and fortune, and promoting wasteful and selfish mass consumerism.
Since Riley as you say like many sailors hates to put on the engine and would rather sail in light winds. I would expect he might look into Electric Propulsion on their next Cat or maybe a retrofit. It would fit in well with his sailing modes. I expect him to pay a visit to Outremer since they are in Europe with some of the Catamaran designs he has been working on driving Elyna crazy talking about them. Or at the very least get a new helm seat to replace the one that got washed over board on this trip
I imagine that Riley understands enough about engineering, to know that electric propulsion is not realistic for the worldwide cruising that he does. Plus, now that he is a dad, I imagine that he doesn't want to risk times when they might find themselves stuck out at sea, waiting for either the wind to blow, or the sun to recharge his batteries.