Block Anonymous Access to Teams without GSA

Documentation states that anonymous access to Teams and Sharepoint can be blocked on the data plane with TrV2 through GSA. 

Testing TrV2 with a browser extension (Modheader) to inject the TrV2 header I found that injecting this header also to "data plane", ie Teams.microsoft.com does block anonymous access to Teams.

I am wondering if this method could be safely used to block anonymous access to specific M365 service until a potential move to GSA