Captains "do what they have to do" all the time with or without players consent. That comes with a leadership role in general. It's easy to say what is "shady" and what is not, but the reality is that sometimes they break rules to improve the overall better picture.
Firstly, I question your "4.5" claim. Unless you had a "touring pro" playing for you I seriously doubt anyone would get DQ'ed at the 4.5 "S" level and certainly not a DQ resulting in match score reversals/defaults. For someone to be DQ'ed as a 4.5 "S" they would have either be literally a touring pro or using an alternate account and/or alias. Even if they guy played D1 singles the year before, he can still self-rate as a 5.0 and appeal down to a 4.5. Even if he gets "DQ'ed" in the first year, it would be a ratings DQ and would not result in all of his/her matches being overturned.
Secondly, captains always "do deals" amongst themselves. Sometimes this is to protect a 5 line default, miscommunication, or be "social". Sometimes they do this to protect their players or themselves.
"In the 1980's two men dominated--sometimes each other, most of the time everyone else."