If I use IPFS, it's my understanding that my node not only caches content that I request but also content that other nodes might request.
By default, your node will only cache content you request. It'll only cache content on behalf of others if you run a public gateway (or some website you visits requests the content through your local gateway).
If a peer asks for content your node doesn't have, you node just won't give it to them (it won't go looking for it).
OT: Digital searches are performed by the CBP (at the border as a part of customs), not the TSA (they only care about the physical security of the airport): https://www.eff.org/wp/digital-privacy-us-border-2017