Yes, it is not a good idea to invest money in only one Altcoin, but maybe he sees that the price of Siacoin will be high in the future, therefore he wants to keep it until the time set by him, I think Siacoin looks good if he is very good at trading There is nothing wrong with putting money into one Altcoin, because he may be able to assess and see a graph of how the Altcoin will move in the future.