Here's why....

Kris Kobach was ruled by a court in Kansas to have wrongly discarded 18,000 ballots as Secretary of State....never mind using money that the state didn't have for his wild goose chase.

Ken Blackwell oversaw the release of private information of millions of voters--twice--as Secretary of State of Ohio.  He also insisted on the use of less-than-stellar Diebold voting machines in 2004....after repeated requests by others in government to not use them.  2 months after the election, he purchased stock in Diebold.

They're both working for a president that is a serial liar.

In short, I wouldn't trust these people to bury a dead mouse, let alone oversee a commission with any level of impartiality.    

As far as trying to hide something....I could say the same about Trump's tax returns.

As far as the HRC/ 3 million votes comment goes...that is something Trump is obsessed with.  Blame him for bringing that up in the first place.