Can you point me to the actual source of your opinion? Just to make sure we are looking at the same thing. I took a look at ITF officiating here:
https://www.itftennis.com/officiating/rulebooks/pro-circuit.aspx and downloaded
2018 Pro Circuit Regulations. Of our interest herein is article 4 On-site offences, and in particular sections D (time violation), section E (audible obscenity) and section G (verbal abuse), and section J (abuse of racquets). Firstly, I note that time violation results in "fault" (for server) while the other three violations of interest are assessed in accordance with the Point Penalty Schedule. So Moxie is right above: time violation is just a fault and does not incur progressive penalty.
More importantly to me, you are correct that "F words" are penalised in the same way as "calling umpire a thief". But it's worth noting that "F word" falls into a different category of violations E (audible obscenity). So, e.g. Serena in 2009, with her threat to "shove a f..ing ball in f..ing throat of a lineswoman" should have been doubly penalised (for both sections E & G), but the officials did not clearly enforce the double penalty: i.e. they turned out to be lenient by citing one offence only (G verbal abuse). Since then, Serena worked on her behaviour to avoid violating section E but she forgot about section G, on which she still must work.
To clarify section E, we need to read what is "audible obscenity":
audible obscenity is defined as the use of words commonly known and understood to be profane and uttered clearly and loudly enough to be heard by the Court Officials or spectators. - ITF Rules 2018.
The key here is "loudly enough to be heard". So, in case of Sir Andy, even if he says his F words very visibly (everyone can deduce it from his hippopotamus mouth) but his words cannot be heard, then technically he cannot be charged with audible obscenity violation. And he is smart enough to shout his F words mostly at a time when there is a loud background noise at the stadium, to make sure his obscenity is not audible.