Yes, this is quite correct although here the string "5E0" is meaning something different that "zero but true". Here it means "hey, this is a special kind of Five!". But we get the same idea of expressing 2 things with a single return value. Here the idea expressed is that this is the "END" and the END value is 5.

E0 means 10**0 which is "1" numerically.
So, 5E0 is a way of saying 5*1.
The E0 means that this is a "special Five" and indeed it is with the flip-flop operator.

0E0 is way of saying "0*1". And that this is a special zero.
demerphq pointed out that 0E5 is also zero, the exponent doesn't matter. This means 0 * 10**5. However I see a certain simplicity to E0 (10**0)== 1.