The Blackstone IPO and the '40 Act

The AFL-CIO has written to the SEC requesting that the Commission make a "detailed inquiry" into whether the Blackstone Group IPO is an investment company.  The letter is here.  To the extent regulated as an investment company, the Blackstone Group LP would be subjected to the more severe regulatory framework imposed under the Investment Company Act of 1940.  Any such inquiry by the Commission would presumably slow down the IPO process.