So the new Missions, unholy incursion has arrived and this is the blub from NC:

Based on the community's feedback we're offering separate tiers of rewards and an extended period: this week-long event will conclude on June 29, so every player will be able to join and meet the criteria. There will be three special named enemies from the three participating Fallen Astartes Legions (Alpha Legion, Black Legion and Word Bearers.)

Seems not as unless you are a lvl 50 anyway it won't let you travel to the areas. or is there some other weird and illogical reason?