Unable to remove dynamic line inside Dynamics

[Jay Anderson]

\version "2.13.32"

justCresc = #(make-music 'CrescendoEvent 'span-direction START
'span-type 'text 'span-text "cresc." 'tweaks '((style . none)))

\new Staff \relative c'
{
  c1\justCresc | %Works as desired
  c |
  c\! |
}

\new PianoStaff
<<
  \new Staff \relative c' { c1 | c | c | c | c | }
  \new Dynamics
  {
    s\justCresc | %Dashed line shows here
    s |
    \override Dynamics.DynamicTextSpanner #'style = #'none
    s1\cresc |
    s |
    s\! |
  }
  \new Staff \relative c' { c1 | c | c | c | c | }
>>

\justCresc works as I want inside a Staff. Inside of Dynamics,
however, the line still shows up. Any ideas how to make not show there
without "\override Dynamics.DynamicTextSpanner #'style = #'none"?
Thanks.

-----Jay