Well for the 'timely manner'. Its 2 months later now and the Asus websites still offers this beta as the latest firmware version.I don't see how else they can, 1. protect their customers in a timely manner and 2. without fully testing a solution first, do otherwise.
"Please be noted this is a quick fix beta version for DNSmasq vulnerabilities" :-S
I think that 2 months should have been enough to offer a official version of its firmware