I guess if you believe every unsubstantiated hysterical rumor posted on the internet, conjecturing a bullshit theory to support those rumors seems....perfectly logical.
I won't disturb your bullshit theory by pointing out that if the government wanted N for executions, they could legally obtain pharmaceutical-grade real N; they would have no need to use half-potency black-market N from a mexican veterinarian.
The Federal and State Governments are indeed finding it difficult to source appropriate supplies of phenobarbital. The stuff is there, alright, but manufacturers will not supply for execution use. The EU has banned the sale for execution use, and within the US companies like Pfizer refuse to supply too, and they place a contractual block on their customers on selling on to government agencies for capital punishment use.
Many state governments are looking to their legal alternative methods of execution in order to get around any shortages. Some states allow condemned persons to choose their method of death, from a short shortlist, and this right may have to be legislatively withdrawn.
As the newspapers tell us, Federal authorities are currently restarting the procedure of carrying out executions, and have initially scheduled the executions of five men on Federal Death Rows.
It's interesting to note that three (I think) states are potentially introducing nitrogen gas inhalation as an alternative. None, AFAIK have actually used it yet. Alabama, Mississippi and Oklahoma.