I assumed it was an exaggeration, like 48 hours with a break to sleep, because how could OP even know for sure that it was truly 48 hours without break if the guy was at home?
I'm still suspicious whether it was actually 48 hours straight with no rest because -- no matter how brilliant someone is -- I would be extremely leery of the code written toward the end of that session.
I suspect people who were around for the dotcom bubble, or who have worked on consumer software back when it had gold master dates, don't read it as an exaggeration. I did not, and know several people who worked non-stop 30-60 hour shifts for various reasons.
In my case one had genuine clinical manic episodes and was open about his mental illness; another seriously burnt out; older friends in the games industry spoke of multi-month post-launch vacations (back in the late 90s) to cool off.
I'm still suspicious whether it was actually 48 hours straight with no rest because -- no matter how brilliant someone is -- I would be extremely leery of the code written toward the end of that session.