"State" field in custom table extended from task is read-only for custom-role end-users

Hi,

I have a custom table A  extended from OOB task table and access control specfic to custom role R. OOB state field in the custom table A is read-only for this custom role users. And when I checked the ACL, there was no write access defined on task table.  If I added ACL to task table with read access what would be the impact on other tables. 

How do I resolve this? 

Thanks.