I don't agree. The term RMS watt may be incorrect (or perhaps redundant) but you can certainly talk about an instantaneous peak watt if you desire. It's simply the instantaneous peak current times the instantaneous peak voltage. And if you average all the instantaneous voltage measurements by the instantaneous current measurements over a time period then you get the average power in watts over that period..........................
There's still no such thing as an 'RMS Watt' though....or a 'peak Watt' or an 'average Watt'. All in common usage . All wrong.