An interesting piece of info on the pitot probes indeed. My attention was caught by one particular sentence:
Should flight safety be concerned, the manufacturer, together with the authorities, issues a mandatory service bulletin followed by an airworthiness directive (AD).
That's not strictly true. It is the case that all Mandatory SBs (and ADs) arise from safety concerns. But I do not believe it to be the case that all flight safety issues automatically result in a mandatory SB or AD.
The Canadian Aviation Regulations, for example, state:
593.02 Unless the Minister considers that an alternative action to an airworthiness directive will ensure an equivalent level of safety, the Minister shall issue, in the form and manner set out in Chapter 593 of the Airworthiness Manual, an airworthiness directive in respect of an aeronautical product for which a type certificate has been issued, or accepted, by the Minister where
(a) an unsafe condition exists in the aeronautical product and the condition is likely to exist or develop in other aeronautical products;
(b) it has been found, subsequent to the issuance of the type certificate, that the aeronautical product does not conform to the requirements of the basis of certification for the type design of the aeronautical product;
(c) it is necessary to modify or cancel the requirements of an airworthiness directive issued by a civil aviation authority having jurisdiction over the type design of the aeronautical product because the Minister considers the airworthiness directive inappropriate for reasons related to the environment, safety, the delayed receipt of an instruction issued by a foreign civil aviation authority or reliance on foreign legislation; or
(d) it is necessary to modify or cancel a Canadian airworthiness directive that is in force, because a condition referred to in any of paragraphs (a) to (c) has changed or ceased to exist.
(my emphasis).
So if the OEM proposes a recommended SB, and believes (and convinces their authority) that the normal replacement cycle, or economic incentive to upgrade, or whatever, will get the parts changed out in time, then no AD is required.
It should be noted in that context that AF was sufficiently concerned to start the replacement of the pitots without needing an AD. Summary: the pitots may well have been a threat to flight safety, just people thought it was of low enough risk to carry the problem and address it without AD-level action.
edit to add that I have no reason to believe EASA are any different to TCCA in this regard, nor the FAA. I know of issues in fact where TCCA have issued an AD for their OEM, but EASA haven't required one for theirs. And I'm sure there are examples in fact of every combination possible)