Uh...probably, yes. Especially with a wiley crafty leader like Tom's Yeerk at the helm. The humans certainly couldn't have tracked him down, and once in Z-Space the Andalites could probably only by chance.
And we know a Blade Ship turned the tide in the initial battle with the Dome/Pool ships in book #1, so they're pretty freakin' substantially powerful.
Tom could absolutely not get away, it was just a matter of how to do it. Rachel was the obvious choice, and both she and Jake knew it. No wrong decision made there whatsoever.