Dear Sir, whilst I agree with your initial reaction, I believe there could be a quite harmless reason behind this loutish and vulgar dress style. Since we can not see everything of the gentlemen's surroundings, it could be inferred that he has just stood up.

For if he were to have been seated, as one should be when having tea, (unless at a lawn soiree), and saw such a marvellous act of unfettered whimsy to be deserving of high praise that an upright ovation was required, he should not have had time to put his refreshing beverage down, nor do up his formal attire in the proper fashion.

Of course, this is no more than a hypothesis, but it shows we should not be judging people so freely. Good day.