Uh why would Caterina bring ANY Bourbon lands back to Antoine? De la Tour lands in Auvergne and Boulogne, sure. The Bourbon-Vendômes lost their title of duke of Bourbon first to Louise of Savoy, Css d'Angoulême, and when she died, her grandson got them. Then when he died in 1545, the title of duc de Bourbon went vacant. I'm not sure if it was restored to Antoine or the Bourbons per se before the ascension of Henri IV.
Either way, Caterina's uncle wants an alliance between François and the Medici, not the Medici and some random French prince who a) isn't very high in the French succession (4e/5e at the time, and most would've laughed at you had you said his son would be king of France); b) not very wealthy (most of the 'good stuff' went to Louise of Savoy; and c) not even in possession of his inheritance (the actual dukedom of Bourbon etc as well as the Alençon lands which ended up in Marguerite d'Angoulême's hands despite her being a childless widow of the last duke, whose main heirs would've been his sisters, the duchesse de Vendôme (Antoine's mom) and the marquise de Monferrat. The marriage between Antoine and Jeanne was a sop to the Bourbons that, in a roundabout way, they were getting the lands that should've been theirs to start with).