Yes, I think it's not necessary.

There are only 16 entries in all of jmdictdb that end with とした(and half of those are coincidental, and not とする forms at all).  A number of others should probably also be dropped in deference to an [adv-to] parent entry. I don't think there is anything particularly special about this entry statistically.

Otherwise there are a mountain of とした forms that could be added.

とした search:
http://www.edrdg.org/jmdictdb/cgi-bin/srchres.py?s1=1&y1=4&t1=とした&src=1&search=Search&svc=jmdict

https://eow.alc.co.jp/search?q=雑然とした
chaotic, cluttered, some others...

https://www.waeijisho.net/i/word.html?id=41956
jumbled-up

https://study-z.net/100160243/3

｢His desk is always messy.｣
（彼のデスクはいつも雑然としている。）
｢This downtown area has a cluttered atmosphere. ｣
（この繁華街の一角は雑然とした雰囲気がある。）

Does not apply to people (it would seem).  If you search 雑然とした男, you find 雑然とした男の部屋.

Figured out "chaotic" from context, but later found that dictionaries back it up. 雑然とした雰囲気 is a common collocation.

Note: 雑然 is marked [adv-to], that means it literally subsumes this entire entry. This can ban be deleted.

Is this how "promiscuous" became a gloss? 

Wiktionary英語版での「promiscuous」の意味
promiscuous
From Latin prōmiscuus (“mixed, not separated”), from prō (“forth”) + misceō (“mix”).

@@ -11,0 +12,5 @@
+<xref type="see" seq="1299450">雑然・ざつぜん</xref>
+<gloss>cluttered (e.g. desk)</gloss>
+<gloss>jumbled (e.g. thoughts)</gloss>
+<gloss>messy (e.g. room)</gloss>
+<gloss>untidy</gloss>
@@ -13 +18 @@
-<gloss>promiscuous</gloss>
+<gloss>chaotic (e.g. lifestyle, atmosphere)</gloss>