1) ... accordion sustain is accomplished by continuing to pull or push the bellows while holding down a note(s) ... that technique has NOTHING to do with sustaining a note on a keyboard or piano ...
2) ... try playing a 3 or 4 octave arpeggio or polyphonic chord on a kb without a sustain peddle - even in the midst of playing a song - and it sounds like crap ... unless someone is using 'lightning like' finger/hand movements to hit a sustain button before playing the notes ...

just my 2 cents worth ...

t.