Parole is an executive action, I see all sorts of legal and political issues, also numerical practical ones.
I 134a is of course not legal enforceable, I assume it is a Political not practical requirement. You have to express willingness, not actually do anything.
I did see a F4 entrant case wanting to know how to sue for support under the I 864 the other day, now that is not likely to encourage brotherly love.