Alec,
The only reason I mention puppy dogs and kittens is because usually people can relate to why I might not want to kill those, not just because they are not popular dishes, but because they are accustomed to the idea that they can have thoughts, memories, feelings and personalities. Ultimately I prefer puppies to cows pigs and chickens by a lot too, but not enough that I can't see the similarities and still want to avoid killing them when possible too.
Chris,
I would like to emphasize that I do not think that everything is sacred. On the contrary, to me nothing is sacred or guaranteed preservation, not even people.
But more importantly, what you are suggesting is a false dichotomy, those two extremes, never killing anything or killing everything, are not at all the only two choices.
Rather, the middle position that I adopt is that each life can be evaluated on its relative merits, rather than assigning everything the same min or max value. If I have a choice to spare only one life between a puppy and a fish, I would probably spare the puppy. Between a dangerous crazed dog that already killed people and a fish, I might spare the fish, etc.
And I don't see how you can compare random scratches with valuable information and the desire of something to live their life happily, again it's a matter of degrees, do you really blanket everything as equally worthless? Even on inanimate objects, the random scratches on my table are way less valuable than the years of data, experiments and pictures I have stored as scratches on my DVD (especially if that's the only copy). Yet you are suggesting I must care equally for the scratches on the table or the shape of a carrot, that does not follow, things are valuable to different degrees.
And while your neuronal connections might be what you identify as you, the random crookedness and scratches on a carrot are not used by the carrot to identify itself, nor by anybody else. The carrot doesn't care about their pattern, you don't care, nobody cares. The patterns in Einstein's brain are something he cared, his friends and families cared about and we all care about and are thankful for, they advanced our civilization and would have been a great irreplaceable loss if they had been destroyed prematurely. They are not the same as scratches on a table or a carrot

About protein supplementation:
Supplemented proteins are better than whole foods when "part of this nutritious breakfast". They have exactly what you need and none of what you don't want or could get from better sources. They are great for long-term consumption too. They are cheaper and yet often mixed in just the right amounts and combinations for best performance and health, according to our best knowledge which is quite a lot.
About the aluminum can example, I don't know who uses those, but you have -exactly- the same problem if you store meat in aluminum or sprinkle aluminum powder on top of meats, the point is, don't do it.
There is no need to have any sort of contaminant in your protein powder, and no negative side effect from such protein supplementation. If you know how to process things properly, you make things better, not worse.
The 200g is not such a blanked statement, as you know there have been several studies on this, and the extra protein above that proportional to your weight doesn't show much of an effect whenever you actually test it rigorously. It won't necessarily hurt, but that's why I made that statement, to put things into the proper ballpark framework.
Now, you obviously enjoy eating larger amounts of meat than most, good for you. I personally eat a decent amount of protein and good-tasting protein powders and supplements, but definitely not as much as you. Not because it's not possible, I would also probably not feel like eating as much meat as you do either even if I did not have ethical reservations against killing animals. And I am sure other people out there could easily match or surpass your protein intake with protein powders, if they like that, it's quite easy as it's cheaper, more purified and readily available.