Explorers often had Zanzibari escorts, or travelled with caravans. It is not unreasonable to have them on the same side as Baluchis. Verney Lovett Cameron travelled with a Baluchi escort on his way to find Livingstone.
The term 'Baluchi' is an all-encompassing one anyway. Some of the so-called Baluchis were native Africans. They came from all over the place, Indians, Arabians, even Turks. The famous guide Sidi Bombay who travelled with Burton, Speke, Stanley and Cameron had served in the Sultan's Baluchi Guard (he had been taken as a slave to India as a youth, learned Hindi and later returned to Africa). Ethnically he was from the Yao people of Nyasaland, 100% African. So in a sense, all those above-mentioned explorers travelled with a Baluchi.

Cameron's Baluchis were still armed with matchlocks in 1873. Chris Peers implies that Sniders, Remingtons or Winchesters were the standard weapons among Zanzibaris by the 1890s. The Sultan's Baluchi forces had been disbanded by that time (1881, it would seem), but individuals continued to serve for many years after that.
I've not heard of Ruga-Ruga serving with explorers, they more often came into (sometimes accidental) conflict with them, causing problems for their warlord leaders. But in colonial times the German authorities made widespread use of them as irregular troops.