I try not to ever rely on autocast either, but it's news to me that a frigate will not colonize automatically.  Sure, if I had the luxury I would hit pause every few seconds of the game and tend to everything that is going on manually, but as you know, in an online MP game this is impossible.

I have many things to do in the opening moments of the game.  I have to drop labs, I have to queue up research, I have to scout, build some units, build a cap, colonize, yadda yadda.  Your attention can't always be at every place at every time.  The damn frig should have colonized.

Built enough scouts - 4 phase lanes so I built 2 scouts, and thus had 1 for each phase lane.  The reason I didn't know he was right next to the asteroid is that I quite literally didn't have TIME to know he was next to the asteroid.  When a scout uncovers a connecting roid, you send the colonizer immediately.  That's what I did.  By the time my scout arrived at his homeworld, my colonizer was already either in phase jump or had already arrived at the asteroid.  But like I said, I was waiting for the message "colony acquired" or whatever, and if that had happened I would have looked and seen his egg in the grav well, and would have seen that my scout had just uncovered his homeworld.  Of course the damn colony frig didn't colonize, so....

Either way, like I said my attention has to be in multiple places at once in the opening phases of the game.  It is quite easy not to realize someone is on top of you the very instant it is possible to know it.  What if you are ordering your capship to another planet?  What if you are trying to busily manually scout with 4 scouts at once?  What if you have to drop some labs or do some research?  Plus, apparently I'm supposed to micro the colony frig to do its job?  On and on.  At the speed the game was running (quite fast), I was doing about all I could possibly do at one time in the opening moments.

Ah, I've been in that situation HW-'roid-HW although I lost that b-c I chose ion bolt instead of colonise...And then the guy got two capships in five minutes and I ended up believing I was beaten (when he had no other fleet) purely due to those shock and awe tactics.  Then I was on the back foot from there so you can guess the result of that.

I prefer never to turn auto-attack on with my colony frigates anyway - as said its more "auto-annoy" than auto-attack.  If I want to kill the Krosov I send stuff in with/after the colony frigate and manually tell the colony frigate to attack it.  That is the only time I'd ever have one of them attack.  That said, abilities should ovveride attack orders.

I think I will not use autoattack on the stupid frig anymore, but thing is I hate jumping back to my planet and seeing the frig just sitting there getting fired right in the face and not doing anything about it, and also believe it or not if you forget to pull the frig or are just too busy to deal with it, it will kill the siege frig so you don't lose your planet.