I would allow it and approve the PR, then I would ask the team lead if he wants to schedule time to update the style guide to cover cases like this, and set up a linter which can ideally autofix any existing code that violates that rule. Not everyone will agree with the rules set by a linter, but they ensure style consistent, and, more importantly, save everyone time and drama related to inconsequential differences in opinion (at least inconsequential to the bottom line).