The reason Koutarou couldn't contact Theia and Ruth was because of Warlord exploding. Warlord had exploded to jam Koutarou's communications.
Forthorthe spaceships usually made use of gravitational waves to communicate. This was a method more reliable than electromagnetic waves, but it was still susceptible to interference. Just like how one could use electromagnetic fields to interfere with electromagnetic waves, gravitational waves could be interfered by using gravitational fields. That was why Warlord's reactor had purposely been overloaded.
“...Because of this interference, not only is communication jammed, but transferring objects is not possible either! Least of all live humans!”
Since communications using gravitational waves couldn't be used, Koutarou was communicating with Clan through the use of electromagnetic waves. Since Clan was further away than the moon, there was a time lag in their communication. And right now, even that slight lag was enough to irritate Koutarou.
“At this rate, Theia will get beaten!”
Thanks to Clan, Koutarou could get a grasp of Elexis's strategy.
Like he had said, Elexis's goal was to defeat Koutarou. Forcibly launching an attack on the surface to draw Koutarou down from space was the first stage of the plan.
The second stage was to lure the Blue Knight to the far side of the moon. In order to minimize the risks, there would be a high chance that either Theia or Elfaria was on the ship. Elexis's goal was to capture and kill them. If the three spaceships ignored the Blue Knight and sent support to the surface, the Blue Knight would have no choice but to reveal itself. And though Theia knew it was a trap, she had no choice but to head to the far side of the moon.
And the third stage was that if Elexis failed to defeat Koutarou on the surface, he would have Warlord self-destruct to keep Koutarou and the others on the surface for a while. By doing that, he would have some time to launch an attack on the Blue Knight that was isolated in space. The first attack also had the purpose of gathering Koutarou and the others and then stalling them.
Elexis's strategy proved effective, and Koutarou and the others were unable to get to Theia and Ruth in space. The Blue Knight was mostly completely automated, but even then it was a bit too much for just Theia and Ruth to control. If they were to go up against three ships, the more help the better. Left stranded on Earth, all they could do was watch the footage of the battle that Clan was streaming from Hazy Moon to them and Koutarou started feeling rushed and impatient.
“Clan-san. Can't we do something with your power?”
Harumi's silver hair swayed in the wind as she asked Clan whose hologram was being displayed by Koutarou's armor. Harumi’s hair had been dyed slightly silver due to the influence of Signaltin's magical power. It gave her a mysterious atmosphere that charmed anyone who saw her.
“...Even if I have the Cradle enter the atmosphere and pick you up, we won't make it in time”
Entering and exiting the atmosphere followed by a 380,000 kilometer trip to the far side of the moon. Even for Forthorthe's advanced technology it was something that would take some time to do.