Yes, kernel is an overloaded term. This is about functions running on GPUs, not Operating System core functionality.

Not specifically those either.

This is about inner product functions in a specific kind of Hilbert spaces, a notion that is very useful in many branches of applied mathematics. Machine learning and functional analysis included.

The name collision is unfortunate.

One unfortunate difficulty is that these kernels don't map so well to GPU kernels unless explicitly embedded in high dimensional spaces. This is one of the reasons why kernel methods has recently fallen out of favour in machine learning - lack of mechanical sympathy. Note this just one reason, there are others.