SET for the following system variables (both GLOBAL and SESSION):
has been allowed only for users with the SUPER privilege.
Let's allow SET for these variables (both GLOBAL and SESSION) also for users with the BINLOG ADMIN privilege.
Note, sql_log_bin is actually a SESSION-only variable (since MariaDB 5.5). However, internally it is still defined as a GLOBAL-and-SESSION variable, while setting the global one is forbidden by non-standard means.