Can a buyer refuse to close over something minor by calling it a material problem?

Not just by labelling it that way — calling something "material" doesn't make it so, and a buyer trying to walk away from a deal has to actually satisfy whatever materiality standard the agreement's specific clause sets out, not simply assert the label and expect it to hold. Courts assessing this kind of dispute look at the actual substance of the issue against the agreement's wording, not at how convincingly one side characterized it.

A buyer who tries to invoke materiality opportunistically over something genuinely minor — to escape a deal for unrelated reasons, like second thoughts or a better opportunity elsewhere — risks being found to have breached the agreement itself by wrongfully refusing to close, which can expose that buyer to damages or even a claim for specific performance forcing the deal through, depending on what remedies the agreement provides. This is exactly why sellers negotiate for tighter, more objective materiality definitions and thresholds wherever possible, precisely to reduce a buyer's room to manufacture an excuse.

If you're a buyer with a genuine concern, document it carefully and get it assessed against your specific clause before refusing to close — and if you're a seller facing a dubious materiality claim, that's worth challenging directly with a Treadstone business lawyer.