Hello,
I've never used Telemac Tools for Matlab yet.
But as a workaround I can suggest you to use this command from the terminal :
runSELAFIN.py chop -f endframe -s endframe T2DRES T2DRES_lastframe
In endframe you put the number corresponding to the last frame, personnally I read it from BlueKenue : I animate and go to the end and click on the date.
T2DRES is the name of your result file
T2DRES_lastframe is the name you want to give to your single frame file
Then it's quite easy from Matlab as you have only one frame.
Hope it helps you until you find the solution with Matlab.
Regards,
Jérémy