actually nvidia are the most flexible. they can use ARM, PowerPC and x86. and when it comes to x86 nvidia can choose both intel or AMD. in the past some people think that AMD will be the only one have the tech to combine their CPU & GPU properly (same case with intel). but to avoid this from becoming an issue nvidia end up acquiring mellanox which is extremely popular for it's interconnect tech. also the past few years nvidia has been building tons of ecosystem. this is where nvidia major strength is. if anything those that against nvidia acquisition of ARM are not really afraid nvidia to withheld ARM best tech to themselves only. with nvidia even if they still have access to all ARM latest tech going forward they won't be able to compete with the complete ecosystem that being provided by nvidia. so to them the moment nvidia allowed to own ARM is the moment they will be dead.