I'd buy the argument that he doesn't know what a sim card was if he didn't follow that up with saying his current (personal) phone was a Blackberry that he's had for 18 months - 2 yrs.
These are actually two unrelated issues. If you are suggesting that because he has a Blackberry,
he has a SIM card so he should know what one is, that's not necessarily true.
Whether or not you have a SIM card is not a property of the device manufacturer (Blackberry, Apple, Motorola, Nokia, etc). It is a property of the wireless carrier, specifically of the underlying cellular technology used by that carrier.
AT&T's cellular technology is called GSM and GSM phones have SIM cards. Verizon's cellular technology is called CDMA and CDMA phones do
not have SIM cards (at least not in the U.S.).
So, if he got his BB from AT&T it does have a SIM card. If he got his BB from Verizon, it does not have a SIM card.
As far as what a SIM card is, it provides a GSM phone with all the information it needs to make and receive calls and/or send and receive data. E.g. the identification number for the phone so that the cell network knows who/where you phone is, the phone number, etc. A GSM phone will not work without a SIM card. It typically does not have personal information on it (address book, e-mails, photos, etc). It's just the technical stuff that the phone needs to work on the cellular network. The SIM card is a tiny little rectangular card with a little notch on one corner. It is often underneath the battery in a phone.
If you and your spouse both have GSM phones and for whatever reason you want to swap phones but don't want to have to tell all your friends that your phone number changed, you and the spouse can swap phones and as long as you put the SIM card from your phone in the spouse's phone and vice-versa, you can make and receive calls with the same number as before. But, if you have a lot of "stuff" on the phone (e-mails, photos, address book, etc) it is going to stay with your original phone unless it is on removable storage.
Now, if you are thinking that your phone has a little tiny card that you put in a slot on the side, that is not a SIM card. That is a Micro SD card. That is used to store personal stuff on (e-mails, photos, etc). It is unrelated to the operation of the phone and the phone will work fine without it, you may just not have any space to store anything.
So, you can debate whether the detective should have known what a SIM card is because he is a detective, but the fact that he has a BB does not tell you anything about his SIM card knowledge.