Go on then, list
all the toilet breaks Murray has taken during a match in his career (not counting going to the loo when already off court for a MTO, a heat break or the roof being closed, etc...).
What I can do is find you an article from 2015 where he discusses toilet breaks
https://www.bbc.co.uk/sport/tennis/33398103 which sounds pretty consistent with his thinking right now.
I have my issues with Murray's ranting and raving on court which I've no doubt has distracted opponents at times but it's clearly not done with malice aforethought since it's quite obviously a visceral reaction and oftentimes self destructive. I can't say I'm aware of him having any kind of reputation for being underhanded.