1) Ryzen is absolutely vulnerable to Spectre, however desperately you don't want to think so. (I don't want it either; I just bought a Threadripper 1950X, after all)
2) If you actually think the eBPF JIT being turned off is going to save you and that Ryzen is magically immune because it's off: you're deluding yourself completely. Thinking eBPF is the key or whatever is a full misread of the actual vulnerability... Attacks never get worse, they only get better. You are guaranteed to see more exploits that do not leverage eBPF, but other components of the kernel to compose gadgets. Modern systems are millions of LOC; there's ample surface area for this to happen.
2) If you actually think the eBPF JIT being turned off is going to save you and that Ryzen is magically immune because it's off: you're deluding yourself completely. Thinking eBPF is the key or whatever is a full misread of the actual vulnerability... Attacks never get worse, they only get better. You are guaranteed to see more exploits that do not leverage eBPF, but other components of the kernel to compose gadgets. Modern systems are millions of LOC; there's ample surface area for this to happen.