Cert is an award and 10pts/$ on free night equals zero points.. and you got points on original stay and no doubt used your cert on a top priced hotel which the hotel that caused Your cert to be issued will be billed for in full by Hilton Corporate

You may get 1k Myway points though

To my mind it would only be annoying/unfair if you added multiple paid nights too and by having the one cert night count as award mean HH as usual treat whole stay as award earning zero points for paid nights too