In a way, yes. (I assume 'going through the book' includes doing exercises, not just reading).
Think of it this way. Is a PhD in combinatorics from the math department, with exposure to programming, the most suitable candidate for the job of building OS, DBMS, PL, VM, Compilers? I don't think so. If (s)he is interested in such a role, (s)he can definitely do a good job. But (s)he would have to be aware that roughly 90% of what (s)he learned and enjoyed while doing combinatorics research would not be relevant to the job. The hiring would depend on a combination of how much of that lifestyle (s)he is willing to give up for this job, as opposed to trying to find a tenure track faculty position where (s)he could continue pursuing research, and how much the software company thinks about the enthusiasm of the candidate (to switch from research to software development).
Going through TAOCP and doing exercises and learning relevant math is a close approximation to that, IMO. Keep in mind that a significant number of exercises in TAOCP are about proving theorems.
If Bill (a) has the position(s) and (b) says TAOCP master is best candidate, then yes the person is "the most suitable candidate" for whatever job he has in mind. The End.
Besides, I can teach anyone software development. Kids do it with Scratch, average people did it with BASIC in school, and lay business people used COBOL, Excel, and Visual Basic. I'm sure someone who can learn everything from algorithm optimization to assembler coding can handle C++ with some on-the-job learning. In all likelihood, they already were programming in various languages if they tried to get such a job.
Nonetheless, Bill says they're a good hire for stuff at Microsoft. That's where it went from "I wonder" to "Yes they are." No need to speculate.
Think of it this way. Is a PhD in combinatorics from the math department, with exposure to programming, the most suitable candidate for the job of building OS, DBMS, PL, VM, Compilers? I don't think so. If (s)he is interested in such a role, (s)he can definitely do a good job. But (s)he would have to be aware that roughly 90% of what (s)he learned and enjoyed while doing combinatorics research would not be relevant to the job. The hiring would depend on a combination of how much of that lifestyle (s)he is willing to give up for this job, as opposed to trying to find a tenure track faculty position where (s)he could continue pursuing research, and how much the software company thinks about the enthusiasm of the candidate (to switch from research to software development).
Going through TAOCP and doing exercises and learning relevant math is a close approximation to that, IMO. Keep in mind that a significant number of exercises in TAOCP are about proving theorems.