If I were you and I actually wanted my resume to be kept confidential (although I am at a loss as to understand how and why a resume is confidential), the best way to do so would be to not mark it "confidential" and I would not seal it.

First, neither marking the exterior envelope "confidential" nor sealing it makes it less likely that TSA will look at it. Second, it is highly unlikely that TSA would want to look in the envelope unless there were a secondary screening of your carry on and it appears that there is something other than paper in the envelope.

In that latter case, TSA certainly can open the envelope and sift through the materials.

If this it's really that big a deal to keep your resume confidential, email it to yourself an print the copies out at your hotel or a local Fedex office or somesuch.