I think you're reading a stronger argument into the original article than is present. He's not arguing that Roberts is constitutionally guaranteed this power, or anything of the sort. Just that under current law, he has this power, and under current law, it's a lifetime appointment since the position that grants such power, Chief Justice of the Supreme Court, is also a lifetime appointment.
Journalists who write on legal topics have an ethical obligation to provide proper context to their readers, few of whom have any legal training. Frankly, I think that journalists ought to have a JD themselves before covering these topics, in much the same way tht science journalists ought to have a BS.
If your argument is that Klein is wrong because the very rules of the game could be changed by congress, then we have to consider the likelihood of such an event, probably based upon history.
Has Congress intervened since the court was set up? Are they likely to?
Could we just agree within the current rules of the game specified by Congress, Klein is correct?
No, we cannot agree that Klein is correct. The gist of what he's saying is as wrong as the lede of his article.
1. They have a great deal of trouble doing anything right now. This will blow over before that changes. 2. This is pretty much a solved problem as far as they're concerned. Congress tends to tack "solutions" on top of "solutions". They rarely refactor.
gist of what he's saying is as wrong
Unless Congress changes things, what he said is exactly correct. Within that context, he's right. Maybe you're arguing that he has the wrong context, but I'd argue that we should probably assume that congress isn't going to change those particular rules of the game at this point.
Lack of simplicity in law is a serious problem, but not the main one, at least in this case. The problem is that laws increase the arbitrary powers of government, and rarely if every restrict them.
In most cases, such as the patriot act, they will simply find that vaguest provision and interpret it in the broadest way possible, And, in this case, that interpretation is also secret. The rest of the text is basically filler.
In which case Congress would not pass anything he wouldn't really like (except at the level of personal politics).