Problem is, unless they extend Nico again, there's a big hole at 2B next year and not much internally to fill that hole and 2B isn't typically a position with many good players in FA (or generally) and next year's crop of 2B/SS/3B doesn't look that good. Triantos isn't good enough a prospect to bank on.
Several key Cubs players becoming FA next offseason. Signing a 3B this offseason would make that transition easier. It's possible they go over the LT a bit this offseason to sign both a quality SP and quality 3B and drop back under the LT in 2027 as cheap younger players like Shaw, Caissie, Mo, Alcantara, Wiggins step in to replace more expensive players like Nico, Happ, Seiya, Taillon/Boyd, Kelly next year. Maybe they re-sign 1 or 2 of those vets or sign other vets in FA, but the net result is likely to save them some payroll.