First of all, whether the stroke is a shu is out of the question -- it is not a vertical and long stroke, but typically tilted and short.
Regarding the difference between dian and pie, I must call your attention to CJKV strokes:
Note in stroke "d" (dian) there are two versions, left and right, but both have the stop(顿) at the bottom end. While in stroke "p"(pie) the stop is at the top. One can find fonts that goes either ways: my browser displays it as a pie, e.g..
But we can go one step further and ask: should that stroke be written as a dian, or a pie? Since different authorities may make up different standards.
According to the standard for mainland China: (character 0174)
we can see the stop is clearly at the bottom, therefore, this stroke should be written as a dian, in mainland China.
In Taiwan, there is a different standard, and according to them: (character 101305) http://language.moe.gov.tw/001/Upload/files/SITE_CONTENT/M0001/MU/mua12.htm it is also unambiguously a dian.
In Japan, they also have a different standard: (page 84, lower middle) http://www.bunka.go.jp/kokugo_nihongo/sisaku/joho/joho/kijun/naikaku/pdf/joyokanjihyo_20101130.pdf we can see it is also a dian.
The authority of classical chinese language, the Kang Xi Dictionary (upper right): http://tool.httpcn.com/Html/KangXi/Pic/375.shtml also prints the character with a dian.
While I don't know enough korean or vietnamese to look it up (edits welcome), I think we have enough evidence to conclude with great certainty, that the stroke is supposed to be written as a dian.
But feel free to write a pie instead, I'm certainly not going to judge or be confused which character it is.