I don't get it. It will actually be bad for BOTH chains if indeed Bitcoin forks into two. Some people who are following the space could see this as a weakness and another reason not to start investing or accepting BTC as payments. Imagine if you were a merchant and you have to go thru and be involved in this sh*t, with all the debates and the drama. And worst of all the uncertainty of BTC's future.
Because one of them wants to allow Bitcoin to scale, the other doesn't. duh
I think merchants will support BTC more than BU at least in the beginning because they have been using bitcoin for sometime now and all of a sudden they may not be comfortable in accepting BU. Yes, it can cause some uncertainties which can make the price to correct in the case of BTC. And BU like any other altcoin may get pumped and then dumped, like what happened to Zcash.