Shared records using access team, Forms are read only in UI but form state in JS as 'Update'

Hi,

According to users requirement, I am sharing records across business units, using Access Teams. Record is read only, but ribbon buttons are enable. 

I wanted to make ribbon buttons hidden or disabled.

I am checking FormType using Javascript(Xrm.Page.ui.getFormType()),  getting value as '2' i.e. 'Update' mode. Ideally form is read only. Form Type output should be '3' i.e. ReadOnly.

Second option, checking fields on form whether disabled using JS (Xrm.Page.getControl(arg).getDisabled()), output on 'main' form as disabled = true. But in ISH(Interactive Service Hub) form, getting value as 'false'.(Ideally it should work same in both forms.)

Third option checking business unit and user role in JS and give permissions accordingly.

CRM version is CRM 2016 and working on main and ISH forms. 

Is there any other simple approach? Please suggest.

Thanks in Advance

Akshata