Most of the threat from relativistic jets is from within ones own galaxy (and at worst, its local group). So, yes as the universe expands the risk from the latt

Most of the threat from relativistic jets is from within ones own galaxy (and at worst, its local group). So, yes as the universe expands the risk from the latter should decrease, the risk from the former wouldn't really change due to expansion. The risk probably does still come down, but more due to age as larger clouds of gas get used up and spread around by supernovae, preventing enough mass from gathering for the things that produce relativistic jets. One possible answer to the Fermi paradox is that we're early because the universe may have only recently gotten calm enough for life to survive long enough to develop intelligence.