Unfortunately a company would disagree. Limiters are already bypassed as well so that would not solve the issue. A tragic story none the less.

Add a 6mph limiter and you effectively eliminate all of your jogging, biking and public transport players. Niantic already lossed a third of its user base. That would be another third easily. Cant take that financial hit. People need to heed warnings is all.

Max spawn time has been confirmed at 60minutes. Although percentage rates are ~93% 15 min and ~7% 30-60 min. I have seen this in game myself.