Find rows in which the column doesn't contain a "space"

I suggest you provide explicitly the characters you want to be considered as "white space" and excluded to a regex:

where name !~ '[ \t\v\b\r\n\u00a0]'

Characters:

\s         white space (space, \r, \n, \t, \v, \f)
' '        space
\t         (horizontal) tab
\v         vertical tab
\b         backspace
\r         carriage return
\n         newline
\f         form feed
\u00a0     non-breaking space
---

See the docs for pattern matching.

In your example, note that \xC2A0 is the UTF-8 representation of Non breaking space (00A0).

There exist a multitude of space characters as per the following Unicode listing:

Unicode Characters in the 'Separator, Space' Category

I would extend the where clause in ypercubeᵀᴹ's answer to:
(edit: added \ at the beginning of the string]

where name !~ '[\u0020\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202f\u205f\u3000]'

Characters:

u0020 SPACE
u00A0 NO-BREAK SPACE
u1680 OGHAM SPACE MARK
u2000 EN QUAD
u2001 EM QUAD
U2002 EN SPACE
u2003 EM SPACE
u2004 THREE-PER-EM SPACE
u2005 FOUR-PER-EM SPACE
u2006 SIX-PER-EM SPACE
u2007 FIGURE SPACE
u2008 PUNCTUATION SPACE
u2009 THIN SPACE
u200A HAIR SPACE
u202f NARROW NO-BREAK SPACE
u205f MEDIUM MATHEMATICAL SPACE
u3000 IDEGRAPHIC SPACE

.... and test and test again.