Gohan nor Kuririn would have been able to take out Kiwi, Dodoria, or Zarbon, so if any of them had found the two, that would have ended their attempts right there. If they had somehow managed to beat them, Freeza would have just sent for the Ginyu Tokusentai again, and since Gohan and Kuririn would have lost to the weakest member of the group (Gurd) had it not been for Vegeta’s interference, there’s no way they would have been able to get around the others.
Goku would have arrived, but even if he had transformed into a Super Saiya-jin right then as a result of Gohan and Kuririn being dead, his battle power would have only been 4,500,000, which Freeza would have been able to swat away in his true form like it was nothing.
Let’s say that somehow everything up to Goku being put into the healing chamber somehow still did happen, you’re forgetting that Vegeta held off Freeza at two rather significant points of the overall fight with him, and if he hadn’t been there, Gohan and the others would have been killed before Goku had managed to get out. He held Freeza out for awhile after he had returned to find the Dragonballs had been used (which ended up resulting in Freeza eventually transforming), and then was Freeza’s focus for a good while following his transformation back into his true form.
If Vegeta hadn’t been there on Namek, Gohan and Kuririn wouldn’t have survived near as long as they did, and Goku would have followed suit too. He’s a lot more crucial to what happened than you’re giving him credit for.