neglect, careless, lax
踈 centers on a lack of attention or care: neglecting duties, being careless, or acting in a lax, inattentive way.
踈 is a variant form of 疎, which combines 足 (foot) with 束 (bundle). The exact historical development is uncertain, but the character likely relates to the idea of being sparse or loose, extended to neglect or carelessness.
The left side is 足 (foot) and the right side is 束 (bundle). Imagine a foot carelessly kicking a bundle aside, showing neglect and a lax attitude.
For ソ, picture someone so careless they sew a bundle shut with their foot: sew -> ソ, and the sloppy work shows neglect.