Nominalization with 「ん」and its use for humans (「そんなん入れるよーじゃおしまいだな」)

Taken from 「イエスタデイをうたって3」:

Three guys of an indie band are having a talk about the current situation of their band and the place where they usually have their performances. While discussing their upcoming performance one of the guys mentions that a famous high-schooler-band will have a gig in the same club at the same night, so they expect it to be crowded. After hearing that they say:

「ウソ　やつ　そんな　若ぇの？」

「あのコヤもそんなん入れるよーじゃおしまいだな」

I already checked out this post: What are the rules for substituting の with ん?

In accordance, I think that 「ん」here is just a phonological phenomenon, but with the same „ability“ to nominalize adjectives as 「の」. Jisho lists 「こんな」as pre-noun adjective, yet I assume that it can be nominalized with 「の」like other adjectives as well. Therefore the 「そんなん」in the sentence above would be a noun (?).

If the above is correct, my question would be in how far 「の」can be used for people without being inherently derogatory? While the statement above is not friendly in general, I was thinking about a dialogue like:

「どんな男性が好きですか？」

「優しいの」

Would this answer be acceptable? Even if it is acceptable are there more appropriate alternatives?

Please let me know if my conclusions about nominalization are blatantly wrong.