'Forceful, often vindictive anger'
That's not the right spirit. The Sevens is essentially a great, big cuddly love-in where there's nary a voice raised in anger. And when there is it's usually done with tongue in cheek. Such as when the Australians take their bow to a traditional chorus of boos. Taken the wrong way, of course, the New Zealanders' haka could be seen as 'rugby rage' incarnate - it is derived from a war chant, after all. And whenever Fiji face Samoa there are looks (and tackles) that could kill. But perhaps real wrath will only come to the Sevens if this hypothetical ever came to pass - 'Whaddya mean, no more beer?!'