After reaching out to Microsoft, it turns out the solution is. He said it was looking for a True or False value and it applies to all of the classifications currently.
$ResourceGroup = ""
$Server = ""
$Database = ""
$Values = @('1' )
Set-AzureRmSqlDatabaseVulnerabilityAssessmentRuleBaseline -ResourceGroupName $ResourceGroup -ServerName $Server -DatabaseName $Database -RuleId "VA1288" -BaselineResult $Values