How do you know they weren't happy working for Apple? Maybe they just wanted a bigger payout, which is what founding members of the company presumably just got.
Well based on the press reports at the time, GW III and friends wanted to do a server CPU, Apple wasn't interested, so they left and founded their own company focused on designing an ARM server CPU. So maybe "not happy working for Apple" isn't the correct way to say it, more "not happy with the direction Apple was giving them about what to design". If those reports are true, I don't see him and those he brought with him from Apple being any more happy about the direction Qualcomm gives them about what to design if like Apple they are also uninterested in servers.
If they wanted a bigger payout, they have no reason to stick around at Qualcomm once their lockup expires, so it doesn't make much difference which scenario is true. I just don't see them sticking around past that date if Qualcomm isn't entering the server market.
I'm still kind of annoyed by Apple's decision here, as even before Apple announced M1 and ARM Macs were just a rumor I thought Apple could leverage the solution they would use for the Mac Pro in servers. Not to sell on the open market, but to use in their own cloud. That would be cheaper than building systems around someone else's CPUs, help amortize the NRE associated with the higher end ARM Mac designs, and would have kept GW III and friends around.
Though since cloud servers don't require a lot of cores per system but instead a lot of cores per rack, they wouldn't need to even do something comparable to what the Mac Pro will get. They could build "servers" (more of a line card plugging into a chassis like UCS) around a single M1 Max and probably manage 2000 - 4000 cores per rack at current rack power density levels - depending on how much RAM they'd need and whether they'd have to swap LPDDR for DIMMs to reach it. So maybe they are/will still do their own servers, just not with something solely targeted at servers like GW III reportedly wanted them to do.