You shouldn't care. Because not reading someone under arrest the Miranda warning is constitutionally irrelevant in and of itself. It only acquires relevance if the government seeks to have the statements admitted at trial.
Discussing the similar case of Faisal Shahzad, who attempted to bomb Times Square, Orin Kerr, a law professor who is an expert on the 4th Amendment wrote:
"Importantly, though, it would not have violated Shahzad’s constitutional rights to not read him his Miranda rights. A lot of people assume that the police are required to read a suspect his rights when he is arrested. That is, they assume that one of a person’s rights is the right to be read their rights. It often happens that way on Law & Order, but that’s not what the law actually requires. Under Chavez v. Martinez, 538 U.S. 760 (2003), it is lawful for the police to not read a suspect his Miranda rights, interrogate him, and then obtain a statement that would be inadmissible in court. Chavez holds that a person’s constitutional rights are violated only if the prosecution tries to have the statement admitted in court. See id. at 772-73. Indeed, the prosecution is even allowed to admit any physical evidence discovered as a fruit of the statement obtained in violation of Miranda — only the actual statement is excluded. See United States v. Patane, 542 U.S. 630 (2004). So while it may sound weird, it turns out that obtaining a statement outside Miranda but not admitting it in court is lawful."
Oops, link: http://www.volokh.com/2010/05/05/shahzad-and-miranda-rights/
Discussing the similar case of Faisal Shahzad, who attempted to bomb Times Square, Orin Kerr, a law professor who is an expert on the 4th Amendment wrote:
"Importantly, though, it would not have violated Shahzad’s constitutional rights to not read him his Miranda rights. A lot of people assume that the police are required to read a suspect his rights when he is arrested. That is, they assume that one of a person’s rights is the right to be read their rights. It often happens that way on Law & Order, but that’s not what the law actually requires. Under Chavez v. Martinez, 538 U.S. 760 (2003), it is lawful for the police to not read a suspect his Miranda rights, interrogate him, and then obtain a statement that would be inadmissible in court. Chavez holds that a person’s constitutional rights are violated only if the prosecution tries to have the statement admitted in court. See id. at 772-73. Indeed, the prosecution is even allowed to admit any physical evidence discovered as a fruit of the statement obtained in violation of Miranda — only the actual statement is excluded. See United States v. Patane, 542 U.S. 630 (2004). So while it may sound weird, it turns out that obtaining a statement outside Miranda but not admitting it in court is lawful."
Oops, link: http://www.volokh.com/2010/05/05/shahzad-and-miranda-rights/