But Gingrich wasn’t “lobbying for ideas” at all. He was the one who was advising others who themselves wanted ideas on how to get something they wanted accomplished.
Gingrich was writing books and putting out statements on positions that aligned with his clients interests all through this period. That is lobbying for ideas, not registered-with-Congress-and-knocking-on-Congressional-doors-to-pitch-his-legislation lobbying.
Likely, he was also using his “nonprofit” activities to satisfy the interest of his “for profit” clients as well. Another legal loophole commonly used in the Beltway.
And he was, according to plausible but not on-record confirmed reports, steering his clients to which Congressmen would be amenable to which arguments, etc..