If it was bad enough to delay the flt it was bad enough to wait for maintenance. Doing a start with a leaky engine with pax loaded , a puddle under said engine and I guess nobody outside on the headset to monitor for fire or to use an extinguisher if req'd was just a tad risky.
The one thing the old "wise" pilot did get right was many engine fuel leaks do heal up when seals are moved / pressurised etc. The rest was unacceptable risk imho.
Engine leaks/weeps, seeps are tolerated to given amounts by the AMM but should be assessed first.