If you want to do some trading better to do with all of your coin, there is so pointless if you are just using 2 btc of your total coin, that is not even half of your balance to do trading. If you can manage to use high amount to trade I believe that you will earn a quick cash. Because bitcoin price is really volatile so you can take advantage in this kind of trading
Well i asume he does not have any knowledge in trading, so i suggest using that 2 bitcoin for trading while learning. Because trading with zero knowledge is too risky. If he's confident enough, then he can use the other one or keep using the 2 btc.
2 btc is really good amount to start trading with especially if you are trading altcoins, buy cheap coins with a descent volume and if price boosts then it will give you some best returns but if you are on learning curve then its better to start with 0.1 or 0.2 btc and gain some practical experience of trading.