The Foundation's public filings are online, and I think they only had $22k in donations last year. Doesn't mean his contributions were all charitable, but they don't appear to have gone to the Foundation at least.
How much would you bet against most (or all?) of Matt's "donations" being money he spent to keep wordpress.org running? (which he explicitly admits is not owned by the WordPress Foundation, but is owned by Matt personally)
For all we know these are self-dealing tax write-offs to his own foundation. The one that is currently doing dirty work for his private business.