i think both can be related as well as it could be a coincidence. relatedness possibilities are numerous as East African Coast of the "INDIAN" Ocean had been trading with Malabar Coast and Beyond and were connected by land since eternity. But, as Lion is one of the most prominent animal in all languages throughout the history. And Lions were found all over the world as well. Therefore introduction of the word, to and from India (or Indo-european) and Africa (sawahili) origins is equally plausible.
On the other hand, convergent evolution in human societies is a common occurrence. seemingly independent groups of people developed similar tools, skills, social structures and designs. similarly many words in unrelated languages often sound similar because ultimately all words originated from sounds. e.g. words describing sounds, animal sounds and natural phenomenological sounds and sounds associated with basic human actions and emotions like yawning, coughing, sobbing, laughing, etc.
Thus both convergent development or built-in tendencies or genetically determined human social and intellectual progress resulting in similarities between unrelated societal groups should be explored more. And at the same time we should be open minded in examining the possibility of complex interactions and relations among distant societies. Trans-Atlantic Pre-Columbian interactions have recently been discussed, similarly ancient Indo-African interaction and diffusion should also be explored further.