Something got garbled here -- apologies if it's my fault, please cite your source and I'll try to fix it upstream.
The PHP (but much simpler) server side embedded mini-language idea was part of LiveWire, and would never have made it into the Netscape browser instead of JS. Rather, it was intended to do conditional server-side markup, string interpolation based on HTTP header values, etc.
Upper management -- Rick Schell, VP Engineering -- argued "we already have two languages, we can't justify three". The two were Java and JS. This killed the PHP-like exercise.
I rushed JS for many reasons:
1. Everyone at Netscape was rushing, because Microsoft was coming after Netscape and we all knew it. People were working around the clock. This was not healthy, but it happened.
2. There was little time to get the rest of the browser JS integration (AKA "the DOM Level 0") done in the rest of calendar year 1995 before the code froze for Netscape 2.0 final. The first public beta was in the fall, and code freeze in early fall or even late summer (my memory fails me here) meant critical bug fixes only after that point.
3. The Netscape IPO was coming up, which added to (1).
4. JS was called Mocha, then LiveScript, but Netscape marketing wanted to get the JS trademark, which required showing Sun that a VB-like companion to Java was viable. Some of the rushing was based on trying to keep Sun on board, in the person of Bill Joy (who eventually signed the trademark license for Sun, as "Bill Joy, Founder, Sun Microsystems").
5. LiveWire wanted JS frozen as its server-side language, and was on its own hard-charging schedule. I think it was trying to release with Netscape 2, but again my memory fails me. Anyone reading this who was there should weigh in.
/be