No. Trading only one symbol does not automatically trigger the rule.
For example, you can trade only XAUUSD. That alone is not banned.
The issue is not whether you trade one symbol. The issue is whether your trading activity or exposure becomes too concentrated in one direction on that symbol.
Example:
If you trade XAUUSD only, but your trades include a mix of BUY and SELL activity, or your directional concentration remains below the 70% threshold, the condition may not be active.
However, if almost all of your activity or exposure is concentrated in XAUUSD BUY, or almost all of it is concentrated in XAUUSD SELL, the metric may become active once the 70% threshold is reached.