Seems like a lot of Gibson bashing and anecdotal evidence being brought up here.
I've played plenty of GC And Sam Ash off the shelf Gibsons, Fenders Epiphones, Squiers, Musicman, Sterlings and Ibanez as well as the occasional used Ric, Warwick and Hofner. I find that nearly all of them are in need of a set up and nearly all of them have some QC nit that I can pick. Are there Gibson fanboys, yes - just like there are Fender fanboys and the one thing they both have in common is spreading negative disinformation about the other.
To the OP - just like any critical diagnosis from a doctor - when an unknown guitar tech says its busted and can't be adjusted or fixed get a second opinion from a trusted tech. You might just find that guitar you so loved but thought was defective is only in need of an adjustment by a competent luthier, likewise you might get a confirmation that it is junk and should be returned. Nothing to lose and everything to gain. And until you have first hand experience to confirm some of those "Gibson basses are junk" claims I'd write them off as rants from competing brand fanboys.
Full disclosure: I have well over 30 basses and only one of them is a Gibson. It's had zero issues and I've been very pleased with it, just like most of my other non Gibson basses.