Yep, he’s opted out after opting in.

Mark Schmitt has a fairly detailed analysis of the legalities, and it basically comes down as follows:

• There has been an advisory ruling that candidates can change their mind until they actually receive the matching funds.
• He took out a loan for his campaign, but it was not contingent on matching funds, and he is not in the position of renouncing, “an asset if it’s entangled in another transaction”.
• Because there is no quorum for the FEC, there can be no rulings.

So he appears legal, although he also appears to be a hypocrite.