As I was not alive at the time of the Heysel disaster, I cannot answer you there - I instead put you in the direction of my esteemed and knowledgable fellow Reds fans who would be glad to put you straight on that one.
As for us 'pulling the rug out from under the feet of' Boston Red Sox, I imagine that John W. Henry himself would freely admit that if he were not capable of managing both ventures successfully and without bias he would not have put forward a bid.