Despite what I said earlier, I'm now a bit iffy on the inability to attack - if you go by the first condition that you only suffer the effects of obstacles if you overlapped due to a maneuver, then you would ignore the entirety of the text in the obstacle types. That text is where you're told a ship can't attack. You can't really cherry pick which effects you suffer and which you don't, so by a literal reading of the obstacle rules, a ship tractored onto an asteroid suffers no effects that round.
I agreed with (and so do the rules) everything you said UNTIL this paragraph.
The rules regarding Astriods are spelled out and "not attacking" when your ship base is on top of/touching an asteroid is explained in a complete sentence on its own. There is no stipulation that one must occur for the other to happen. There is no stipulation that you must manuever on to the rock to be unable to attack. It reads as a sentence, complete and on its own, without any stipulations to how you arrived on that asteroid.
"While a ship is overlapping an asteroid, it cannot perform any attacks."
That's it. Read that sentence on its own.