It WAS open to interpretation, until "The Other," at which point, the ONLY way to explain Spider-Man's transformation was if you accepted that Ezekiel's interpretation of his origin was 100-percent correct.
Also, it bears mentioning that, in Ezekiel's final story arc, JMS devoted a TWO-PAGE SEQUENCE to nothing but Ezekiel STARING AT THE READER and haranguing the reader with complaints about all the fan objections to his attempted retcons (on the third page, you find out Ezekiel is talking to Peter). It was an INCREDIBLY pissy and self-indulgent example of Author On Board and Take That, to use the TV Tropes phrases.
And the storyline that introduced Morlun and Ezekiel both was completely devoid of redeeming virtues. Ezekiel was introduced as a stranger whom Peter knew nothing about, but Peter instantly trusted him and believed everything he said, and Morlun is built up as a serious threat by having Peter SAY, "Wow, I've NEVER fought anyone this powerful before, and I've NEVER fought anyone who's made me MAD before!" Whether it's mystical or sci-fi or whatever the fuck else, THIS IS BAD FAN FICTION WRITING, PERIOD, THE END. If Chuck Austen had written the exact same words, we wouldn't even be DEBATING this.