That's right. Apparently they let us land because they weren't afraid of a single ship, but they would undoubtedly blast it at an invading fleet.
7 seconds sound clip from the Radar Men from the Moon - Molten Terror (S1E2) movie soundboard.
You can hear this line at 00:03:44.240 in the Blu-ray version of the movie.
Quote context
[...]
- Do you think he'll be able to do it?
- What did you find out about the ray guns?
- Then hadn't we better go back right away and warn our people?
- No.
- All you've got to do is get the gun. That may not be too tough.
[...]