To be honest with you, I really dont know... (sorry)
But I DO know that oxygen cleansers work to oxidise and this is a very different method to Epsom Salts (which draw water into the bowel like a Salt Water Flush) and I would assume that because you can take oxygen cleansers very long term (something no trecommended with Epsom Salt due to hypermagnesia) then I would think that the magnesium isnt absorbed and therefore wont dialate the bile ducts.
This is just my speculation of course...
If I was in your siutation I would probably put off the cleanse till tomorrow to make sure I performed it correctly.
Or I'd take a teaspoon of ES now, wait 2 hrs then flush, if I was feeling brave and willing to test out something new without knowing the consequences.