In regards to the tether thing, your opponent probably just dropped off a fraction of a microsecond before you let the tether go. You probably didn't realize they dropped off because it was kind of a "bang-bang" play.
Hey guys guess what.
In teams, if Olimar is doing an upthrow, and he gets interrupted, the Uthrow animation will still go, but Olimar will be able to do anything. So check this out:
I was testing this a couple nights ago. I grabbed my opponent, then had Falco shoot a laser at me right before I did the Uthrow. I got hit, and while the Uthrow animation was going on, I was able to do an upsmash.
Most of Olimar's super AT's are situational, and this is definitely no exception. But regardless, if some genius out there can figure out a way to have Olimar release himself from the Uthrow animation without outside help, that would raaaape.
Fino, I need to send you this.