MCT is nothing more than a carrier's willingness to accept the risk of a misconnect. That means rebooking, duty of care, and possibly compensation and a refund.
Whether a given connection is within SCT (Sensible Connection Time) is entirely personal and requires consideration of your personal circumstances and the significance to you of being on time.
But the BA-BA MCT for LHR is never less than 90 minutes, so Google Flights is entirely correct.