I can't tell if Tom Petty is merely nuts or just a sentimental old fool.
Number one, you got your gear stolen because of the idiots running that studio. There should have been closed-circuit monitoring of the facility. You would have gotten your gear back by now if there was. So, it stands to reason someone working at the facility grabbed the gear.
Number two, the police don't care. Unless they are vintage instrument buffs, they aren't going to work in shifts to solve this case. No CC-TV? No chance.
Number three, the vintage instrument myth is alive and well. Someone is going to pay top dollar for these instruments on the vintage instrument black market and end up with an old guitar that they can only play in the privacy of their own home. Aside from being weird, who really thinks that an aged, broken-in piece of wood with strings on it is all that special?
They have done tests on the violins made by Stradivarius, for example. Those tests revealed that vintage violins are no different in sound or performance than newer ones. And so, what you have, is a myth that surrounds these old instruments. Petty could take half of his money and go out and buy new instruments all around and, once fitted with adequate pickups and amplification, would sound the same. There is no special timbre or resonance from a vintage electric guitar. That's just what those clowns running music stores want you to think.
Petty must be sentimental; perhaps he thinks that his vintage guitars are worth saving from the black market. I commend him for that. But this whole thing about vintage instruments is one of the biggest bullshit stories that has survived into modern times.