I don't think this is a good move by Arm, or one in the best interests of the ecosystem. If IP can't transfer from an acquired company to the acquiring company, even if both have an architectural license, that greatly reduces the value of ARM-compatible semiconductor vendors with custom cores on the M&A market. Additionally, Nuvia being successful benefits the overall ecosystem.
I suspect this will end up being settled, but if not, it seems self-defeating.
Without knowing the terms of the ALAs for Qualcomm and Nuvia, I'm not so sure this reflects badly on the ecosystem. If ARM is simply enforcing contracts that Qualcomm thought they could knowingly violate because ARM would look the other way because Qualcomm is one of their biggest licensees, or they were "worried about the ecosystem", or they were busy trying to sell/IPO itself, this isn't going to influence the decision making of other ARM licensees or potential licensees. Indeed, to the extent that Qualcomm's competitors who are also ARM licensees (Mediatek, Samsung, etc.) may be indirectly helped by enforcement of Qualcomm's licensing terms it wouldn't be seen as a negative by the ARM community at large. If you are playing by the rules with your license, you want others held to the same standard.
I think everyone has implicitly assumed that all architectural licenses were the same - at least other than Apple's which is rumored to be unique given their status as a former owner/founder of ARM. Under that assumption it seems obvious that one architectural licensee buying another allows IP covered under one ALA to transfer to another, which is why this lawsuit seems to have come out of left field. No one was questioning whether Qualcomm would have any trouble utilizing Nuvia's IP.
If ALAs are each somewhat unique in terms - perhaps based on what type of devices chips containing the licensed designs will be used in, or payment / royalty schedules based on anticipated volumes, etc. then that obvious conclusion no longer holds. Even had we known that, I'm pretty sure everyone would still have assumed that Qualcomm squared things away with ARM prior to finalizing the Nuvia acquisition. When you spend $1.4 billion you do your homework first, right? (unless you are Elon Musk)
When a company that is considering a $1.4 billion acquisition performs due diligence, you'd have to assume reading the license agreement that affects the major reason you feel they are worth $1.4 billion would be part of that due diligence! Qualcomm would already have access to their own ALA and know what terms it contains. If their ALA includes terms like "non transferable" or was not a pro forma template signed without any clauses specific to Qualcomm's intended market/use of designs arising from their ALA you'd want to look at Nuvia's ALA, right? Maybe they did, but made a calculation ARM wouldn't enforce its terms.
We only know ARM's side from their filing so far, so it is too early to judge. But if their characterization is at all accurate, Qualcomm is in trouble. I disagree that holding licensees to the terms of the license they signed would be a bad thing for the ARM ecosystem. It is in the best interests of those licensees who are living within the terms of their licenses (whether architectural or more standard core licenses) for those terms to be enforced for everyone. It is also in their best interests for ARM to receive sufficient licensing revenue so they can continue to update the architecture and design new licensable cores.