Product template "property_account_expense_id" and "property_account_creditor_price_difference" fields must stay editable in cases even if not "can be puchased". Since it being readonly is trivial, better leave it writeable instead of implementing cross module readonly logic. closes odoo/odoo#150601 Task: 3695677 Signed-off-by: Florian Gilbert (flg) <flg@odoo.com>