Unfortunately not. According to the press release,
This simplified edition, featuring less buttons, reduces the chance of little-ones accidentally exiting their favourite show or leaving the kids UI. It also looks the part with a fun design featuring new NOW TV Kids character - Jessie.
I think what they've decided is that removing the home and app buttons means children can't exit the kids area by mistake by pressing the wrong key (i.e the Home or Sky Store key) and instead would have to deliberately exit the area using the back key and the stay/leave trip-switch.
However because the remote needs a back key then as you say it can be still be used to access everything except the box's secret menus.