by only looking at the source (haven't installed it) I'm guessing this leaks ipv6 addresses and probably shouldn't be used. this is the second openvpn install script to match that description today.
In the past, I've had a habit of passing "ipv6.disable=1" (a.k.a. the "nuclear option") to the kernel on hosts I manage. I'm trying to get away from that, though, and lately, I've simply been dropping "everything IPv6" in my rulesets to avoid things like this.