Nothing he said discounts what you added. You should have just said "be careful with strings" and linked your link, rather than making some vague hand waving correction which wasn't...
It's not a complicated thing it does at all: it uses the standard system facilities for opening an object file to scan through the data section instead of the entire file. In the '80s, it used a.out format, which was dead simple. Today, GNU strings uses the GNU libbfd library, which is quite a bit more complicated, although the fundamental process of parsing an ELF file is also not that complicated.
The actual problem here is that such a dumb simple task as parsing an ELF file isn't something you'll do without vulnerabilities, if you're not paying attention to vulnerabilities. Run `man elf` on your favorite Linux system, and you'll see docs of <elf.h>, which you can use to read ELF files. Write something to just dump the text section -- it shouldn't take you more than like 30 lines of C. Then tell me how many integer overflows you managed to squeeze in those 30 lines. :)
Nothing he said discounts what you added. You should have just said "be careful with strings" and linked your link, rather than making some vague hand waving correction which wasn't...