Bootloader for razr m can be unlocked. Update to Kitkat to unlock. I have successfully updated to Kitkat and unlocked bootloader.
Follow the points in order to upgrade to kitkat and unlock bootloader.
1). Download 4.4.2 kitkat sbf (VZW_XT907_4.4.2-KDA20.62-10.1_CFC_1FF.xml.zip)
http://www.drdevs.com/devs/livinginkaos/FXZ%20files/XT907%20(Droid%20RAZR%20M)/
or
https://drive.google.com/file/d/0Byqu946SkZuqU1AyTTZQUW41M28/edit?usp=sharing
2). Install Java (1.7 or later) if not already installed. http://www.oracle.com/technetwork/java/javase/downloads/java-se-jre-7-download-432155.html
3). Download RSDScriptGenerator from https://drive.google.com/file/d/0Byqu946SkZuqQ2pGNWlUT1M3YUE/edit?usp=sharing
4). Extract the zip file from step 1 and copy RSDScriptGenerator inside the extracted folder.
5). Run RSDScriptGenerator.jar and select the xml file and then click on generate scripts. It will generate 3 xml files FULL, KEEP-DATA and UNIVERSAL.
6). Select Keep-Data if you want to keep all the apps and data or universal for full flash.
7). Now connect your razr m in ap fastboot mode and flash using rsdlite 6.1.4
8). After flash download and install towelroot (tr.apk) from https://towelroot.com/ by clicking on lambda image. This will root the device by installing super user.
9). Install motopocalypse apk from https://drive.google.com/file/d/0Byqu946SkZuqbFhVSFVpQVBQS3M/edit?usp=sharing
10). Start motopocalypse and press unlock bootloader. Provide permission once it asks for root permission.
11). Boot into ap fastboot and check status code 3 and unlocked.
Note: I will not be responsible if you brick your device in the unlock process.