Yes, of course a foreigner who studies Chinese can read pinyin. You should also add the tones because they are important.

The thing is a foreigner can learn to speak some Chinese by using Pinyin, it's considered much easier to get start. but the drawback is as big as it's convenience. As you know Chinese words is actually composed by charactors and you can arrange these charactors to create new words. so if you can only read pinyin and don't know the charactors, then everytime you encontered a new combination of the pinyin (containing the same charators or part of them)you get lost, in this way it's hardly say you know Chinese, you are just a Chinese tone imitator.

Yes, it would be much easier to learn only pinyin instead of 汉字. But if that guy really wants to learn the chinese language and culture, it's important that he gets used to reading 汉字, as pinyin is only useful to help pronounce words.

please use both pin1yin1 and chinese characters. it help them a lot. so they dont get confused.

Most foreigners who learn Chinese start by studying pinyin, otherwise it's almost impossible to get a handle on the tones!