I pulled the XML data for one test from the VersionOne Rest API and noticed a relation named "TestStatus" and then it had a number '9123' assigned to it. So I moved that test manually to 'In Testing' and the "TestStatus" changed to '9121'. Then I moved it to failed and the "TestStatus" changed to '155'. I repeated this with several tests from different testsets and noticed that the numbers for each status were consistent and then changed the code slightly and then I was able to programmatically change the status of each test. I changed "Status.Name" to "Status" and "Passed" to "TestStatus:9123" and now it moves the test into the passed category programmatically.
internal void TestStatusPassed(string str_TestID)
{
var testId = Oid.FromToken(str_TestID, _context.MetaModel);
var query = new Query(testId);
var testType = _context.MetaModel.GetAssetType("Test");
var sourceAttribute = testType.GetAttributeDefinition("Status");
query.Selection.Add(sourceAttribute);
var result = _context.Services.Retrieve(query);
var test = result.Assets[0];
var oldSource = GetValue(test.GetAttribute(sourceAttribute).Value);
test.SetAttributeValue(sourceAttribute, "TestStatus:9123");
_context.Services.Save(test);
}