No, God does not change.
When a mans position changes relative to God there may appear to be a change, but that change can be characterized as God's influence over a man as a man enters into fellowship with God.
A Man who walks outside the influence of Gods Order might:
Smoke
Drink
Do Drugs
Eat Pork
Any Factory meat
the list is endless
But if that man enters Gods sphere of influence he may abandon all of those things for many reasons
I was in the medical field long enough and at a level where I could see the influences of many of the things listed above.
So, another Law, or "Point of Order" engages me. That being that I am part of the Temple.
Do I then consider antibiotics, hormones, stockyard practices, GMO grains etc, etc when I consider what I may or may not eat?
I know I am speaking to a man who thinks, so you can answer that. So then perhaps I will eat deer, that should be fine, or should it? I live in Rural America and I know the grasses in our pastures are poisonous. Petroleum based fertilizers, systemic herbicides like 2 4 D are in all the pasture grasses, not to mention the runoff into streams, creeks, rivers.
Water is another consideration. Did you know almost all municipal water systems have unhealthy levels of estrogen? Women take birth control, piss out the excess estrogen, it goes into the waste system and in municipalities that reclaim and reuse their water the estrogen remains after the purification process. Now young men, especially in larger municipalities are essentially being given doses of hormones that combat the male hormone testosterone. You can think through the "pathogenesis" of the sudden uptick of sins of transgender and homosexuality! If you think you have gone back to the original catalyst, go further! I'm not giving transgenders and homosexuals a pass at all, but there is culpability everywhere!
I could go on regarding the essential commandment to guard the temple and whether it is written or not that certain meats are "kosher" or acceptable "scripturally" must be considered but in light of all the above and more!
Here are a few questions for you:
I have listed just a few of the influences on food and water today which I think you will agree are significant, so:
What were the influences on animal flesh prior to the flood?
What were the influences on animal flesh after the flood?
Men are intelligent, I know what the influences of pork flesh are on the Human vascular system over other meats. It is staggering! Don't you think many men, thinking men, observant men, have over time put two and two together and recognized the harm certain foods had on peoples lives?
Similar to my observation above, do you think men who entered into God's sphere of influence would receive wisdom and instruction from being within that sphere? If so, might that wisdom be recorded according to men's proximity to God?
When Paul says as you cite it; "all food is clean if received with thanks" doesn't he also say;
1Co 6:12 KJV All things are lawful unto me, but all things are not expedient: all things are lawful for me, but I will not be brought under the power of any.
Technically speaking we could say that most meat, fish included, and even water today, and hey, lets put it all in there even fruits and vegetables are poisonous. Is poisonous food and drink expedient?
I think we both know the honest answer, so what do we do with all of the commercial food and water of today? If we eat it are we sinning against the temple? If so, then what? Now we are getting into territory where we might even say a person who choses safe alternatives is fleeing "coming out of Babylon", or the Babylonian system of commercial control to avoid her plagues and so on ans so forth!
I have answered your core question which you already knew and your peripheral questions are volleyed back to you. No, I'm not a doctor, or lawyer as EG says. My formal education is moderate, but my Creator has opened my eyes to "see" some of the things here.