Task: Set Edit rights without the right to delete via HybridDictio

Hello,

I a task which is assigned to a user. This user receives rights for that
task via a hybrid dictionary. At the moment, he receives Admin rights

This includes the right to delete the task. The other enumeration values of
SPRoleType which grant edit rights include the right to delete the task as
well.

Is there a possibility to grant edit rights for a single task without
granting the right to delete it?

Thank you in advance

Code snippet:
HybridDictionary permsCollection = new HybridDictionary();

permsCollection.Add(TaskObject.TaskProperties.AssignedTo, SPRoleTypeEnum);

TaskObject.SpecialPermissions = permsCollection;

( SPRoleTypeEnum has the value SPRoleType.Administrator.
TaskObject is of the type Microsoft.SharePoint.WorkflowActions.CreateTask )