Rather than seperation into positive and negative like you see in NaCl, SiO2 is a crystal rather than a molecule. It won't break into a positive and negative side in water like other dipoles.

So you'd see it either go left (which is to say form a crystal with the bond which doesnt happen due to hydrogen being more attracted to negative oxygen than o2 or Si) or go right (become surrounded by them) but remain as a whole particle. Particles that dont break their bonds just suspend in the solvent.

Since the whole compound is less attractive to either side of the dipole than other water molecules itself, the more dense compound will eventually just sink and seperate rather than break down covalent bonds.

When molecules share electrons equally in a covalent bond there is no net electrical charge across the molecule and therefore no attraction to positive or negative charges.

Ie h2 or o2 or whatever. Any noble gasses. Anything like that isnt charged.