If you want a quick hack then it's possible you could change this in the qa_page_q_post_rules function. There are various array keys like $rules['answerbutton'] that determine whether the buttons are viewed.
At the end of the function before the return, you could set
$rules['answerbutton'] = true;
$rules['commentbutton'] = true;
Which should keep them visible. Note that it might mess with the other logic, like showing buttons to logged-out users (they wouldn't be able to actually comment though).