NotEqual Fluent Validation validator with client side validation

Adapter.js

(function ($) {
    $.validator.addMethod("notequal", function (value, element, param) {
        if (param.indexOf("#") == -1) return value != param;
        return value != $(param).val();
    }, $.validator.messages.notequal);

    $.validator.unobtrusive.adapters.add("notequal", ["field"], function (options) {
        options.rules["notequal"] = options.params.field;
        if (options.message) options.messages["notequal"] = options.message;
    });
})(jQuery);  

Global.asax.cs

FluentValidationModelValidatorProvider.Configure(provider =>
{
    provider.Add(typeof(NotEqualValidator), (metadata, context, description, validator) => new NotEqualClientRule(metadata, context, description, validator));
});

index.cshtml

@model Test.Models.PersonModel
@using (Html.BeginForm())
{
    @Html.TextBoxFor(x => x.First)
    @Html.ValidationMessageFor(x => x.First)
    @Html.TextBoxFor(x => x.Last)
    @Html.ValidationMessageFor(x => x.Last)
    <button type="submit">OK</button>
}

PersonModel.cs

[Validator(typeof(PersonValidator))]
public class PersonModel
{
    public string First { get; set; }
    public string Last { get; set; }
}
public class PersonValidator : AbstractValidator<PersonModel>
{
    public PersonValidator()
    {
        RuleFor(x => x.First).NotEqual(x => x.Last);
    }
}

PropertyValidator.cs

public class NotEqualClientRule : FluentValidationPropertyValidator {

    public static ModelValidator Create(ModelMetadata meta, ControllerContext context, PropertyRule propertyDescription, IPropertyValidator validator) {
        return new NotEqualClientRule(meta, context, propertyDescription, validator);
    }

    public NotEqualClientRule(ModelMetadata metadata, ControllerContext controllerContext, PropertyRule propertyDescription, IPropertyValidator validator)
        : base(metadata, controllerContext, propertyDescription, validator) {
        ShouldValidate = false; //This is necessary - don't want to kick in during model binding.
    }

    public override IEnumerable<ModelClientValidationRule> GetClientValidationRules() {
        if (!this.ShouldGenerateClientSideRules()) {
            yield break;
        }

        var validator = Validator as NotEqualValidator;

        var errorMessage = new MessageFormatter()
            .BuildMessage(validator.ErrorMessageSource.GetString());

        var rule = new ModelClientValidationRule {
            ErrorMessage = errorMessage,
            ValidationType = "notequal"
        };

        if (validator.MemberToCompare != null) {
            rule.ValidationParameters["field"] = String.Format("#{0}", validator.MemberToCompare.Name);
        } else {
            rule.ValidationParameters["field"] = validator.ValueToCompare;
        }

        yield return rule;
    }
}