No one should criticise the Venerable unless they have walked a thousand miles in his shoes, or wearing the robes.
According to the Vinaya rule, it is allowable to obey kings.
Even if it is an offence, it is a minor one, and a personal choice that one can make.
As a young monk, I remember meeting the Queen at an Opening Ceremony for some cultural event, along with Venerable Dr Hammalawa Saddhatissa and some other senior monks. We all shook her hand — an offence of wrong doing for a monk, but refusing to shake her hand would have resulted in many non-Buddhists getting a negative impression of Buddhism, so it was the right thing to do in the circumstances.
Normally, if a woman tries to shake my hand, it is in a situation where I can explain why, and there are no cameras, so at worst I shall offend one or two persons.