Actually quite the opposite - from what I read, MixCloud did get into arrangements with numerous labels/rights holders and therefore the risk of having a mix taken down is greatly reduced - and it's why MixCloud doesn't approve of people uploading individual tracks.
DJs are in the derivative work business, no matter how much they claim to be innovative or 'making something new!' by mixing tracks together, and while I'm an advocate for Copyright Reform, for now the way laws and commercial rules are written, DJs making and uploading mixes don't have a leg to stand on in the SoundCloud model.
