Earlier quoted context omitted.
I meant at a global level (think as if you're attacking all wireguard users, not a single one)
The increased attack surface mostly only affects that one particular implementation though. So, yes, twice as many implementations that may contain exploitable bugs, but each new implementation could only be used to exploit a fraction of the total user base
If anything this is a even a good thing, since it means that each individual vulnerability an attacker finds is less valuable to them.