Do you think that Thel’ Vadam picked up the distress signal Cortana sent out at the end of Halo 3? But why would a Sangheili attack Master Chief at the beginning of the game?
Read Halo: Glasslands.
Rogue Covenant, maybe they picked up the signal.
the “covenant” fleet outside johns ship are probably rouge or have been cut off from the main fleet for a while.
Probable a “splinter” group of covenant
I doubt Thel could give less of -Yoink- about John with the problems he has on Sanghelios.
> Read Halo: Glasslands.
it explains what is happening with the covenant and humans after the war.