> If in the "blah blah blah" he's telling you that your solution is not re-entrant and it's going to crash then you are going to find out he's right.

To be fair to the soothsayers, you could find out you're wrong about reentrancy after the code is in production for two years and some records in the database start having garbage sporadically.

There are some categories of problems where results are king, and some where humility is wiser.