The Red Brigades then operated some high-profile political kidnappings (e.g., Genoa judge Mario Sossi) as well as kidnapping industrialists (e.g., Vallarino Gancia) in order to obtain ransom money, which was their main source of financing.

I was there at the time. I remember the newspapers and newscasts and debate by heart. I was on strike for the first time on the 16 March 1978 as the BR killed 5 security policemen and kidnapped Aldo Moro. But that time was already in the mature period of BR activity.
The so-called symbolic kidnappings were earlier. And I would say they were not just symbolic, often they were aimed at "questioning" or "intelligence" purposes, seen from the BR side.

Given for granted that the original sentence seeds out "labour union leaders", such as Guido Rossa, communist labour union worker, killed in Genoa in his car as he reported to work, it should be pointed out that a few kidnappings had been aimed earlier at right-wing labour union workers. But this was not the rule.

Something totally different were the kidnappings targeted to a ransom and therefore (as the BR used to say) to self-financing. And alongside that the holdups.

The question here is "what should we consider the **executive** quoted in the sentence".

From my personal experience and reminding that era, the BR used to define the establisment they were trying to subvert as "the financial system of the multinational companies".

I am not endorsing or criticizing such views, simply quoting in order to explain. Such criticism (and the armed action of the BR) included a variety of subjects: journalists, magistrates, politicians, policemen, military, "capitalists" sensu lato, and of course managers or as we would ordinarily say in a stricter sense "executives".

IMHO executives in the sentence quoted by the asker are not what we would call "execs" in everyday talk.

They were really **(top) people part of the establishment fought by the BR**: I put top in brackets because often "small brass" were hit. For the BR it was not so important if you were really at the top (also because these people were harder to get at) rather than being part of the **establishment**.
I should add that the BR considered the Italian democracy as an integral part of the establishment.

Last but not least, I based my answer strictly on the context given; I think this looks a bit too concise. Were we trying to recount chronologically what the BR have been in the Seventies and Eighties of last century I would be concerned to a higher degree of analytical prowess. Maurizio