Negative on that.
NP caps are ok for decoupling in small values but not for power supply filtering.
I can't give you the theory on it but I've never seen NP caps used on LM78XX regulators for
the output filter cap. I've only seen electrolytic.
There may not be a reason why it blew but from an electronics 101 standpoint , the only logical
explanation is that the cap was shorted and you didn't know it when you installed it.
I would bet almost any amount of money that you didn't test every single cap with a capacitance meter
before installing them. ( I only do this on high priority prototypes at work if they have a cap meter)
If there is no room for failure on a project you pull out all the stops and test everything .
Obviously nobody does that for home hobbyist projects and very few people ever test any caps, period.
Technically the LM7815 should survive with direct wire short from the output to ground . It should get hot
and shutdown. It may be just a coincidence and the NP cap didn't cause it.
Are you really ready to try to reproduce the issue by removing the electrolytic and putting an NP cap in
there to see if you can blow it up again ?
This may sound nuts to you but when I really want to get to the truth that's how far I'll go.