Completely and utterly false. The exploits being found exist at a point much lower than the x86 instruction set. ARM processors were also hit with speculative execution exploits.
And, his point still stands. While intel has/had meltdown, which was pretty bad. That doesn't mean that a Meltdown like bug doesn't exist in AMD's hardware.
It's like finding a bug in the OpenJDK that isn't in Zulu and then declaring that "Zulu is more secure than the OpenJDK!"
Or an even closer example "Intel doesn't have the TLB bug[0]! Intel makes better CPUs!"
AMD isn't guaranteed free of all exploits. It is only guaranteed to not suffer specifically from meltdown.
Just Not Meltdown. Or SPOILER. Or Fallout. Or RIDL. Or ZombieLoad.
You're really underselling the difference between the two. AMD's processors have only shown vulnerability to the issues that are inherent to the nature of speculative execution (Spectre).
Intel, on the other hand, has suffered from no less than 5 or 6 separate disclosures of vulnerabilities from various places in their microarchitecture where they cut corners on process separation in order to gain speed. None of these exploits have been pulled off against AMD, despite many of the papers authors explicitly trying to,
The original rebuttal was AMD gets less researcher eyeballs because there are more Intel devices in the wild so it's expected that Intel has more vulnerabilities found.
This was fully correct, yet the GP and you apparently are fixated on the idea that AMD didn't have certain vulnerabilities that were originally found _by studying Intel CPUs_. Yet no big surprise most don't apply to AMD in that case... because they were found by studying Intel CPUs first.
Yes they can. Instruction sets are just that, a bunch of op codes and "things" for a processor to do. How a processor actually performs them is open to implementation.
Implementation matters a lot. Heck, it is WHY there are performance differences between AMD and Intel CPUs.