Ingineer: 2011 NEC Article 625.19 (Automatic De-Energization of Cable) "The electric vehicle supply equipment or the cable-connector combination of the equipment shall be provided with an automatic means to de-energize the cable conductors and electric vehicle connector upon exposure to strain that could result in either cable rupture or separation of the cable from the electric connector and exposure of live parts. Automatic means to de-energize the cable conductors and electric vehicle connector shall not be required for portable cord-and-plug-connected electric vehicle supply equipment intended for connection to receptacle outlets rated at 125 volts, single phase, 15 and 20 amperes."
I do not know if any of the portable Nissan 120v EVSEs that have come with the Leaf have the "Automatic De-Energization of Cable" functionality (I have inquired, but not yet gotten in touch with someone who knows) -- and the NEC appears not to require it since these Nissan EVSEs are intended for 15/20a 120v receptacles.
If they do not have this functionality, then it would appear that your 120/240v EVSE Update EVSE violates this article. This would be especially problematic since you have modified the original NEMA 5-15p plug (which can easily pull out of its receptacle w/o damage -- probably why the article does not apply to EVSEs with such plugs) with a locking type plug (either NEMA L6-20p or L6-30p) which is designed NOT to easily pull out if inserted into a corresponding receptacle that is firmly mounted on a wall. Hence an accident resulting in a substantial pulling force on the EVSE's cable while charging could result in pulling apart the receptacle, plug, cord, or cable possibly resulting in the exposure of electrically live wires -- a shock/fire hazard.
However, if these EVSEs do have the "Automatic De-Energization of Cable" functionality, then the EVSE Update does seem to meet this section of the current NEC.