He is "swinging the club held in two hands"
There is nothing wrong with what he is doing - it's not against any principles or spirit and it's perfectly acceptable within the rules
The rule forbids anchoring the club against the body - he isn't anchoring the club against the body - it really can't be any more simple than that
He is putting with his top hand pretty much stationary, acting as a pivot point, and his bottom hand pushing the club through with a pendulum action. Even if this is allowed under a technicality, it is hardly a classic golf swing and IMHO shouldn't be allowed! At the same time as banning anchoring, the R&A/USGA should have restricted the length of putters.