In SA, abelungu in general benefited from Apartheid. It is no comfort to Blacks to tell them that "not all whites hate you", it's just a few goons. This is the mentality that Nkomo had, all the way from the incidents in camps during the war, to "pasi na ngomo" slogans, by ZANLA, to gukurahundi. Nkomo ignored these literally to his personal and his people's peril!
While it may be true that "imfene ngu Mgabe ngokwakhe and a few of his goons", this is hardly any comfort to the millions who are victims of these people. Shonas in general benefit from the policies of these people. They participate willingly. They are not innocent.
Read this! http://rhodesian.server101.com/tidal_wave_of_hate.htm
While the credibility of such documents is hard to establish, the history of the suffering of the people of Matebeleland at the hands of people who habour similar sentiments as expressed in this document is recorded history!
There might be no Shona Grand Plan as such. It could have been the product of Rhodesian agents, as the document is displayed on their website. It is hard to tell!!!
Remember that when the CIO double agent(s) WOODS/CONJWAYO were released they confirmed that so called Super-ZAPU dissidents were SA agents. Woods bemoaned the dissapperance of the 6 tourists in Matebelaand in early 80's as due to overzealousness on the part of these agents(the government was seen as slow in implementing what the boers wished to see happen, hence the drastic step of murdering of international tourists!)
The army deseters who were hounded out or escaped to save their lives were few. They did not have sufficient motivation to "take the fight to Mashonaland" as you suggest. These were personal grivences which they could not take to any body. I personally know two, ex-ZIPRA who were totured. They left and came to Jo'burg. They did not become dissidents!