SEL does what it does well, but with the concern about backdoors, I wouldn’t want to use it.
The public dev community for Linux should be able to spot inadequacies and holes in their kernels, but if it’s done by the NSA under the guise of GPLv2, and nothing can be changed, we really have no idea what’s going on under the hood which is counter to the idea of the GNU to begin with.
If the source is available, you can inspect it before compiling it. Besides. . . . . No Such Agency is subtle. They’ll hide the backdoors in something EVERYONE uses, and never bothers to compile from source. Like Firefox, the BIND daemon, or SSH. . .
These two clauses are mutually excluded. They cannot both be true.