Where does Dumbledore get off?

[cetuaq]

No: HPFGUIDX 74442

You'll have to excuse me if this subject has been beaten to death 
already. But where does Dumbledore get off deciding to take Harry to 
the Dursleys when the Potters have designated Sirius as his guardian? 

Sirius was already there and ready to take custody of Harry. Hagrid 
grabbed the kid and disappeared with him for 18 hours, and Sirius's 
reaction was to go and try to kill Pettigrew and then end up in 
Azkaban for 12 years. 

If Dumbledore hadn't stepped in, wouldn't Harry and Sirius both have 
been better off? And as for protecting Harry from Voldy, wouldn't the 
invisible House of Black have worked just as well as Old Magic? And 
am I the only one who finds Dumbledore's explanation insufficient 
when balanced against 14 years of abuse by the Dursleys?