Investigateislam did not quote the rest of the story which is in the next hadith right after (#559) which says ''Allah's Messenger (may peace be upon him) called him and said to him: 'These Mosques are not places mean for Urine & Filth, but are only for the rememberance of Allah, Prayer and Recitation of Qu'ran''

InvestigateIslam only quoted one hadith out of context & did not finish the story & give the full version of events Where the prophet forbade this, this proves he is a liar

Conclusion

The prophet muhammed is not saying this action itself is permissible nowhere does the hadith say this, he is simply commanding his companions not to shout at the man, and then the prophet ordered them to clear the area and finally he calls the bedwin man over and explains to him this is not acceptable behaviour. As we know the prophet muhammed was a very merciful person, so the prophet Muhammed didnt want people to shout at him because it is quite possible this bedwin arab did not know this was not an acceptable practise, the arabs in pre-islamic Arabia had very little standards, they even used to dance around the kabba naked (islam later aboloshied this evil practise). Therefore the prophet told his companions not to shout at the man and the prophet himself explained to the man that this was not an acceptable practise.The reason he didn’t want to interrupt him is because it is important for a person to be careful not to get urine on his clothing or skin. This may be one of the reasons why the Prophet (peace be upon him) did not allow the man to be interrupted while he was urinating. Most Men will agree that if you have to stop in the middle of urinating, its painfull and difficult to do. It is also important to realise that the masjids back then had a bare dirt floor and a considerable part of it had no roof and was open to the sky, almost like a tent