A "squishy" boot does not mean a leak. What that means is...the boot is SQUISHY. Could be squishy from age. Or fatigue. Could be from an oil leak. The tech simply guessed it was a leak. But he obviously didn't really KNOW. He could have loosened the clamp, to see if any oil seeped out. But he didn't. One reason why I like independent mechanics is it is a lot easier to talk to the guy that does the work. Dealers are for warranty work. Service and tech bulletins. Getting OEM parts. Otherwise find a good independent guy.
At this point you don't have a safety problem. You are alerted to a possible maintenance problem. So you need to look for signs of worsening.
Also like it or not...a woman can have a problem getting a good answer. You obviously know whats going on. Some don't. But the dealer didn't try to snow you. They said if you need a new rack, the job costs about $1,000. But the green check box, indicates you don't need it now. But keep an eye on it.
I see no problem with what the dealer told you. The only problem was the tech should have reported the squishy boot. And he should have informed you of all the possibilities. Not just the worse case scenario.