The downside of immortality is being captured and tortured for centuries.

He actually got stuck in the past during the Bell Riots, but it was never covered in the show, because Berman felt that the plotline, of Miles struggling with the decision to seal himself away in cryo on only the slimest hope of being found in his proper time, if at all, was too similar to other O’Brien episodes. Same reason they cut out the part where Picard finds him with those other frozen people

I watch PBS news daily and I can’t believe I never made the connection.

he would have got the crew to safety as fast as one can say, “energise”.

And he would have gotten to it had he not been constantly bothered with fixing the food replicators.