You should know there are also numerous non-radiometric methods for dating things, and that multiple methods are correlated with each other. For example:
Lake Suigetsu and the 60,000 Year Varve Chronology
Why would both radiometric and non-radiometric methods yield correlated dates if radioactive decay rates varied in the past? It makes no sense.
You do appear to be arguing for a deceptive universe.
Dating Techniques:
*Uranium to Lead --- minerals --- 1M to 4.5B years
*Rubidium to Strontium --- minerals --- 60M to 4.5B years
*Potassium to Argon --- minerals --- 10K to 3B years
*Uranium Series Disequibrium --- minerals, shell, bone, teeth, coral --- 0 to 0.4M years
*Carbon 14 --- minerals, shell, wood, bone, teeth --- 0 to 40K years
*Fission Track --- minerals, natural glass --- 0.5M to 1B years
*Thermoluminsecence --- minerals, natural glass --- 0 to 0.5M years
*Electron Spin Resonance --- minerals, teeth, shell, coral --- 1K to 1M years
*Geomagnetic Polarity --- minerals --- 0.8M to 200M years
*Amino Acid Racemization --- shells, other biocarbonates --- 500 to 0.3M years
*Obsidian Hydration --- natural glass --- 500 to 0.2M years
*Dendrochronology --- tree rings --- 0 to 12K years
*Lichenometry --- lichens --- 100 to 9K years
These and other dating technologies are remarkably consistent with each other. Each of course has its own limitations and like any scientific measurement or calculation each has a range of possible error which is carefully calculated.