Just so that you aren't scared for your friend. Let me tell you this. If you haven't brushed your teeth in a long time, yes your gums are going to bleed because they aren't used to the daily scrubbing that the tooth brush does to them. But if you notice, after a little while of brushing you will start to bleed less and less, until one day you don't bleed at all due to your gums getting used to it.
Or as Aryeh stated. It could be that his gums aren't as strong. In which they have come out with many advances in teeth care. He may need to switch toothpastes and or get a toothbrush that would be easier on his gums.
Tell your friend: You want to GENTLY brush the gums as well. Use a small circular motion. Angle your toothbrush so the bristles go just under the gum line. You should brush a minimum of two minutes twice a day. Brush all areas--inside, outside, top, bottom, front back, right, left. Many people miss the insides of their teeth (especially the inside of the lower back teeth) and canines get missed a lot because they are on the corners and get skipped going from front teeth to back teeth. It may be a little tender the first few times and may bleed but if you keep doing it, they willl toughen up, get healthier and won't bleed or hurt. BRUSH YOUR TONGUE TOO! GAGGING OR NOT, IT'S LOADED WITH BACTERIA!
But, one of the main reasons gums bleed is lack of flossing. Many people who are good brushers don't floss. Ideally, we would like you to floss every day but even a few times a week is better than never. Also, even flossers don't always take the floss under the gums. There are two parts to flossing. When the string breaks through the contact where the teeth touch you are helping to prevent cavities but you also have to floss your gums.
thanks! :3