publish system::expand-deftype ?

Hello, for my library https://github.com/cosmos72/cl-parametric-types I need the function introspect-environment:typexpand, which expands DEFTYPE'd types, similarly to what CL:MACROEXPAND does for macros. Even though introspect-environment does not support ABCL, I found that system::expand-deftype does exactly what I need, yet I am wary of using a non-exported symbol from ABCL. Is system::expand-deftype stable enough to be published as an ABCL extension to ANSI CL and to be used to implement introspect-environment:typexpand ? Regards, Massimiliano