Maybe, or maybe not.
Selling Ralinepag makes some sense if ARNA sees a way to co-market Etrasimod and Olorinab for auto-immune style IBS, IBD, Pain etc etc. Those two are related. (Lorcaserin was likewise related). There are some efficiencies there to be had from sales operations and marketing.
Ralinepag is a totally different specialty. Though I argued at the time it might have been low cost to manage since that market is much easier to find, seems they made a good deal to grab the cash up front, take some back end, and focus on the future.
Perhaps they have not made this very clear to the wider market. But there is some sense to the way they proceeded.
I don't think selling or parntering Etrasimod would give ARNA shareholders all that much value. It's trading at 2x cash give or take. If they sold E how much higher should it go? Even if they had a 20% royalty? It would trade at cash value, less burn, and a factor for ramp to royalties and risk, plus O perceived value. If they paid out a dividend that would factor in.
I am not sure they can or could play it any other way than to say they intend to operate independently but always open to listen to pitches.. but of course I too am open to hear other convincing opinions - many I'm sure have been posited already.