It's a crowded market and they are targeting planes that can replace jets for medium and longer distance. Which at least short term won't be electric. That would require breakthroughs in fuel cells that I think they are starting to conclude are a combination of expensive and impractical. And there's the whole notion that green hydrogen is more of a promise than a reality right now.

Battery electric makes a lot of sense for smaller planes and distances. But that's a very dynamic market with a lot of players and not a lot of clear added value for Rolls-Royce. Also, it's very different from their current market which is basically focused on jet engines for big planes. That stuff is just way out of their comfort zone.

IMHO, the commuter plane market will change quite dramatically in the next decade. Basically battery electric is not a drop in replacement for those planes. But instead that market will start shifting to much simpler and smaller planes that are dirt cheap to manufacture and operate. Basically the main cost is the battery and the maintenance. Add autonomous flight or at least vastly simpler operations to the mix and pilot cost goes down as well.

That enables flying with much more but smaller planes. Which in turn enables flying to and from much smaller airfields closer to where people want to go. With vtol, potentially even inside cities. Long term commuter jets (with fuel cells or sustainable fuel) won't be able to compete on cost for short hops.