Connect is issuing "ALTER TABLE DISABLE KEYS" when inserting data to a connect table pointing to a remote table. I think Connect disables keys for speedy insertion of data and then creates key.
Most of the time users connecting remotely are not having ALTER TABLE privilege. So it becomes impossible for them to insert data using connect.
I suggest that a flag should be added to connect connection parameters to disable/enable connect issuing ALTER TABLE DISABLE KEYS command. I could not find something similar on the connect documentation page.
This way all user can insert data to remote connect table, even if they are not having ALTER TABLE privilege.
Above can be tested using the following steps:
See the above error given by connect.
I have tested it on Debian 8 64bit only.