title_body: Dealing with core argument loss from syntactic applicativization
upvoted_answer: I don't think there are any attested languages that limit the role that relative clause heads can have in the matrix clause. The accessibility hierarchy is a theory explaining the capabilities of various languages to produce relative clauses where the head has specific roles in the relative clause.
  
  If we take your example and exchange  the matrix and embedded clauses, you get the following examples. I'm changing the first example also to use a resumptive pronoun.
  
  1a)  *The telescope that I see Bill with it is on the hill.
  
  2a)   The telescope that I see-app is on the hill.
  
  
  If you want to reintroduce the demoted argument Bill, you can use an adposition or a case. Suppose you reuse the preposition towards for this purpose.
  
  2b)   The telescope that I see-app towards Bill is on the hill.
  
  
  One interesting choice would be to use neither cases nor adpositions.
  
  2c)    The telescope that I see-app Bill is on the hill.
  
  
  Since the embedded clause already has a subject and obliques can't be relativized, that forces the interpretation of Bill as an oblique.