Hello, i need to ensure that a page is not delivered from the Content DeliVery API if it's not allowed. What is the best way, using a ContentFilter or using a ContentApiModelFilter?

We have a requirement that some articles are only allowed in some countries(legal). So the ArticlePage has a custom property where you can configure it. Now i failed to implement it in ContentFilter since it does not seem to be possible to filter the complete content, just to remove/clear some properties. The documentation mentions it: 

"The downside of IContentFilter is that it is still not possible to remove some default properties of ContentApiModel like ExistingLanguages, MasterLanguage, and so on."

But i'm also unable to implement it in a ContentApiModelFilter (just relevant code):

[ServiceConfiguration(typeof(IContentApiModelFilter), Lifecycle = ServiceInstanceScope.Singleton)]
public class ArticleApiModelFilter : ContentApiModelFilterBase
{
	public override void Filter(ContentApiModel contentApiModel, ConverterContext converterContext)
	{
		IsRelevantArticleResult result = IsRelevantArticle(converterContext.ContentReference);
		if (!result.IsRelevant)
		{
			return;
		}

		if (!String.IsNullOrEmpty(result.Article?.ArticleDetails?.AllowedCountries))
		{
			bool isArticleAllowed = IsArticleAllowed(result.Article!); 
			if (!isArticleAllowed)
			{
                               // contentApiModel.Properties.Clear() does also not work
				foreach (string key in contentApiModel.Properties.Keys)
				{
					contentApiModel.Properties[key] = null;
				}
                                
                                contentApiModel.ExistingLanguages = null;
                                contentApiModel.MasterLanguage = null;
                                contentApiModel.ParentLink = null;
                                contentApiModel.Language = null;
                                contentApiModel.StartPublish = null;
                                contentApiModel.StopPublish = null;
				return;
			}
		}
	}
}

The article is added to a ContentArea and the response still contains it(id=7851):

"mainContentArea": [
        {
            "displayOption": "",
            "contentLink": {
                "id": 7851,
                "workId": 0,
                "guidValue": "9ec626ba-c936-4c39-8266-ee5561219198",
                "expanded": {
                    "contentLink": {
                        "id": 7851,
                        "workId": 0,