No, ssh tunneling would help, because the IP packets making up the ssh connection would be coming from the phone, not the laptop, so they would have their TTL set by the phone.

I assumed he meant ssh tunneling from his computer to a home network or something in order to disguise his User Agent or anything else identifying on the application layer. This makes more sense...

I'm using USB tethering (Proxoid), so I don't think the TTL issue applies to me.

Uh, yes, TTL would apply to USB tethering (if that is what they are looking for). TTL is part of IPv4 (it's called hop limit in IPv6) which is a couple levels up from the physical layer (in your case USB) in the OSI model. I mean, whether you use USB, or Ethernet, or WiFi, you're still just shuffling packets around.

Well that sucks. I suppose the best thing to do is have the tethering apps not decrement the TTL, though I have no idea if any of them support that.

Again, it's not the tethering app that does it, it's the TCP stack. It's likely quite possible for a custom Android ROM to implement this workaround, but I would be surprised if you could accomplish that with an iPhone.