Very interesting my friend :-) Thanks for the honest response. I'm glad you're aware of nihilism's core flaw, which is that to claim that "there is no truth" is a claim about truth itself. At least I believe that's what you're aiming at by saying that it's not defensible and that you only make a "strong assertion" with that statement.
However, all of that is exactly what I mean when I say nihilism just isn't useful, not at all in fact; we wouldn't have survived as a species were we all converted to solipsism. That in itself is a strong claim to make, I know. Or, I think I know. Even though I fully agree that "I don't know" may be the most honest claim about any perceived truth, we can only survive and stay sane by living in a world where we do know. Or: use the tools we have to approach truth, which has to be a shared truth, as much as possible.
That's just my two cents though, and mine alone ;-) I fully respect your perspective here and appreciate your response 1000%. Thanks so much :-)