Well, look at it this way... When you're that passionate about something, it can be pretty hard to contain the overwhelming emotions at the time. For example: look at professional athletes who win tournaments, I doubt they're crying because of publicity. This act was a huge deal to Chris Brown, and not to mention it was Michael Jackson's first actual tribute concert after his death.
I will add however that I was neeeever a huge fan of CB after the whole Rhianna incident, but a recent poll I saw online was showing that over 60% people have forgiven him, and in my opinion, for him to step up and put on a show like this for BET in memory of such a legend has me giving him such huge props.