So legal actions he is taking today is "material" to a claim made 7 years earlier? It would have no impact on the case whatsoever. Thus, by definition is not material.
This is why, even Ken Starr, talked about him "lying under oath" and never officially called it "perjury".
"On September 9, Independent Counsel Starr submitted a detailed
report to the Congress in which he contended that there was "substantial and credible information that President William Jefferson Clinton committed acts that may constitute grounds for an impeachment" by
lying under oath in the Jones litigation and obstructing justice by urging Ms. Lewinsky "... to to file an affidavit that the President knew would be false". On September 11, the House of Representatives approved
House Resolution 525 by a vote of 363 to 63 authorizing a review by the
Committee on the Judiciary of the report of the Independent Counsel to determine whether sufficient grounds existed to recommend to the House that an impeachment inquiry be commenced and also approved the public release of the Starr report. On September 21, the Judiciary Committee
released nearly 3,200 pages of material from the grand jury proceedings and the Starr investigation, including transcripts of the tesimony of
President Clinton and
Ms. Lewinsky."
Republicans in congress went on to call it perjury in the hearings but it does not fit the legal definition.
So far as I am concerned I believe what they did was right. What Clinton did was wrong and he was publicly humiliated for that. But I see no evidence that it was perjury.