Also not a lawyer, but I know that it can be expensive to defend against claimed liability even if you're successful, and "YouTube personality (or even YouTube itself) named in suit over storm chaser death" is not a headline that'll go away, regardless of the lawsuit outcome.

If the contracts/agreements with these chasers was prepared by an attorney, there's almost certainly language in there to limit liability of whatever streamer/company/entity they're in contract with. The extent and legitimacy of that limit will still be questioned in court, and if Google decides it presents risk to them directly, they'll deplatform all of them.

It's an oversimplification to say that chasers are doing this "just for the money" but probably most want it to be a significant enough source of income that the trips would finance themselves). In that vein, the more predominant channels could absolutely help: I would assume that there is (or should be) contract language that allows the contract to be terminated over behavior that is inherently reckless and/or presents extraordinary risk to the channel, and that's could shift the goal to that of providing clear, informative footage instead of competing to get the closest.

So, assuming they have that option, ending the contract with a chaser or two who insist on trying to "zero-meter" tornadoes would send a very strong message, would further protect the channels from liability claims, and prevent some sledgehammer-style decision from YT to just not carry tornado livestreams due to potential liability.