[racket] TR Predicates For Mutable Datatypes

To pick up on a previous topic:

OK given define-predicate doesn't work for mutable datatypes.

(define-predicate T? (HashTable Symbol String)) ;; goes boom

Are we also saying in effect that no possible manual predicate construction
will be accepted by TR?
i,e, is there any form of the below one can construct that TR will accept?

(: T? (Any -> Boolean : (HashTable Symbol String)))
(define (T? ht)
  ...)
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