I grepped through the sources of cl.*\.el.  cl-expr-contains and
cl-expr-contains-any are not specific to the loop implementation.  I
think the functions do what their names say, inspect an expression and
count occurrences of symbols.  The comment above cl-expr-contains says
so as well (";;; Count number of times X refers to Y.  Return nil for 0
times.").

I tested my patch for a few hours with my configuration that makes heavy
use of cl.  I have not run in any problem so far.

        Christopher