First, anyone truly concerned about this for actual use cases just isn’t going to bring their phone with them at sensitive times. Especially after the infamous chip bag Italian meta data incident.

Second, it’s conspicuous and kinda suspicious so its use is limited to primarily virtue signaling privacy advocates or crazy people and the latter aren’t usually big spenders.

Third: the engineering sounds challenging. All that metal in an undeployed fashion is going to reflect and interfere with reception. ( it isn’t an iron man suit, it has to get packed somewhere.). That may also interfere with RF safety approvals? Finally, avoiding RF leakage is surprisingly difficult in practice.