What side reactions are suppressed by the use of TMSCl in the acyloin condensation?
The acyloin condensation of diethyl adipate (1) on your Wikipedia citation generates ethoxide that can cause a Dieckmann condensation (intramolecular Claisen condensation, structure 6). TMSCl scavenges ethoxide and silylates the enediolate 3 formed in the acyloin condensation. The process is a 4-electron reduction (see details below). Mild hydrolysis of 4 gives the acyloin 5.