As for your story about Tyr... frankly, once you were defeated...
I wasn't defeated.
I've seen (and been victim of) Tyr's relentless rushes.
No offense meant to Tyr in the slightest, but I wasn't impressed. It was just standard fare as far as I'm concerned. It wasn't any more or less impressive or relentless than the bazzillion other rushes I've seen. I knew it was coming, because for one reason I was playing MP online, LOL. For another reason, my scout uncovered his hw before his uncovered mine, and I saw that it was Tyr, which means "rush" all the more. Finally, when his scout hit my homeworld, it went straight for my contructor and started shooting it. That didn't bother me whatsoever, because I didn't intend on building anything with it, but point being, that was 3rd indicator "rush" was coming. I simply built 1 civ lab on the asteroid I conquered, researched scrapping technology (vasari), then demolished all structures when he rolled into my planet, plus I demolished the civ lab at the roid.
The first thing he did when he rolled in was starbase (vasari). I thought that was funny because he didn't need to - I wasn't going to oppose him in the slightest degree. So that was a waste of funds on his part. The poor starbase never even had a chance to shoot at anything since I scrapped everything the second he rolled in. Looked pretty though, I guess.
This is an example of an attempt at a "strategic counter" to a rush. Let him take what he wants, and just go about your game somewhere else. The problem I'm pointing out is, the game provides for few, if any, such strategic counters. Pretty much the only thing you can do is fight fire with fire.
EDIT:
Secondly, that planet likely had strategic value (why else would you have attacked it?)
LOL. People generally attack planets for the same reason mountain climbers climb mountains - "because they're there."
The reasons I attacked the planets I attacked in the game I just mentioned had nothing to do with their strategic value. One simply needs planets for resources, logistics/tactical slots, etc. When leaving my homeworld and colonizing up the middle, I simply asked myself which planets could I colonize that 1) weren't ice/volc/dead roids, 2) were fastest to get to, 3) had the least resistance, and 4) were in the path or near other planets which met the same criteria. Later when Tyr decided to follow my trail of breadcrumbs, I changed 3 above to 3) had the MOST resistance, so that I could leave that resistance for him to fight, i.e. this meant the planet should have had lesser value to him. It made no difference.
Neither Tyr nor I attacked planets because of any strategic value, but with Tyr this was even less so because HE WENT OUT OF HIS WAY TO NOT ATTACK PLANETS WITH STRATEGIC VALUE (i.e. he went out of his way to ONLY attack my planets, even after I had purposefully switched to attacking less desirable over more desirable planets, LOL).
The bottom line is, a rusher doesn't attack your planets because they have "strategic value." A rusher attacks your planets because that's what a rusher does. A rusher will attack your planets over other planets even if other nearby planets are easier to take, offer higher strategic value, etc.