I'm pretty sure Twitter software engineers are considered more elite than Tesla engineers in the Valley.
Of the engineers I've met, I'd put the Tesla ones as 'smarter'.
but I have inspected plenty of organisations where strong engineering teams are drowned by management bullshit. even found places where most of the individuals, engineering and management both, are arguably competent but the overall organisational decreptitude kills any and all effective work, no matter how heroic or skilled the individual and collective effort gets.
I get twitter has some issues of scale to solve, but its tweets, even netflix would be far more challenging imo.
Tesla engineers likely are drinking the Kool-aid or were not talented enough to get offers at better companies.
Lastly, it's not "just tweets" at their scale. That's like saying Netflix is just storing some video files in CDNs.