ADA Compliant Shower fails inspection?

[NRNR]

I have listed my house, and my downstairs bathroom has an ADA compliant shower stall (is about 6ft wide, 3ft deep with hand rails, and a wheelchair is able to roll into the stall).  My buyer is pushing to have me add glass shower doors to the shower stall so that it is "functional" for her son to use.  The buyers concern is that since there is only a 1/4" ridge (not a lip) on the front of the stall that the water can get all over the place, even though the shower stall drains properly into the center of the shower.  This shower stall was installed by the builder 5 years ago, and met all codes and ADA approval.  So my question is...should I as the seller be open to installing doors for my buyer?  By doing that am I breaking the ADA code for that shower?  or was meeting the code only important in the original sale of the home?