I don't smoke up and my logic is sound. I understand the transitive property and it doesn't apply here.
This is how I read it :
"While wearing hide armor, you can gain a +2 bonus to AC instead of using your Dexterity or Intelligence modifier to determine your AC." --> DEX or INT remain the key modifiers that would benefit your AC in general.
Similarly, Sentinel says, "While you are not wearing heavy armor, you can use your Constitution modifier in place of your Dexterity or Intelligence modifier to determine your AC."
--> Con can be used instead, but so can Dex or Int. Dex/Int didn't vanish, nor were they "swapped" per se. This is not an ability modifier swap feat, it's an ability modifier applying to your AC temporary exchange. You never lost the ability to trade in Dex or Int for something else. They still exist. It's NOT like power swap feats, at all, you do not trade in your power for another power, you agree to use one modifier instead of another, or to not use Dex Int modifiers to AC.
You keep ignoring the terms "instead of" and "in place of". They are the relevant terms. As you say, you agree to use one modifier instead of another. You can't then use something else
also instead of the first option, and suddenly be using both replacements at the same time.
Just to confirm - I noted above that, by your logic, someone with Melee Training (Charisma) and Combat Virtuoso would get to add Charisma twice on attacks with a dilettante melee basic attack power. Do you really believe this to be the case?
You're erroneously reading into the feat as stating something it isn't. You aren't swapping the use of any AC ability modifiers per se, you're suppressing the use of Dex or Int mods, specifically in the narrow case as they apply to determining your AC. The distinction is subtle, but it's there.
"Instead of" and "In place of" refers, yes, to
swapping, the use. If it was simply
suppressing the use of Dex or Int mods, then it would say so.
It's a rules loophole and they should probably plug it
It's not a loophole - both by the obvious intent and the strict wording, what you propose is not allowed by the rules.
I agree, you can't ride your bike AND drive your car at the same time, but this is different. You're merely trying to not drive your car twice, and benefit in a myriad number of ways from that decision. True && True && True == True. Each statement is true individually, and at the same time too. You can, literally, not benefit from Dex / Int to AC as many times as there are grains of sand on the beach.
Not by any logically sound process. Again, you are ignoring the fact that the options are not worded the way you are describing them. They don't say, "If you choose to not benefit from Dex or Int, you can get +2 to AC" and "If you choose to not benefit from Dex or Int, you can add Con to AC."
They, instead, refer to using gaining those benefits
in place of the use of Dex or Int. You can choose with to replace them with, but you can't choose both.
There are two separate, untyped, benefits to not using your car (Dex / Int only), from different sources. Your car still exists, over there, in its driving lot, unused. It didn't disappear for your lack of use, or intention of use. It will even be there for you to use tomorrow if it rains. There is no reason you need to sell your car, to force yourself to ride your bike more often.
You are correct that you can always choose
which option is in effect. You can choose to use Dex or Int, you can choose to use Con, or you can choose to just gain a flat +2.
You own a car, as well as a station wagon and a truck. You can drive the station wagon instead of the car. You can drive the truck instead of the car. Any given day, you can choose from all of these options.
But you can't stack these vehicles on top of each other and drive several of them at the same time.