Interference is a legal term and applies to when human actions are interfering with individuals' or species' activities, habitat or behaviour. Human interaction is what you are actually talking about and it is not forbidden but what interaction is permissible is determined by provincial and federal government regulation on advice from scientists, recovery teams and probably with some input from government officials. As for necessity, that depends on what you are trying to achieve and what interaction is permissible.
What recovery projects try to do is keep as many adult and young peregrines safe and secure while they are at the nestsite. For our Project that means we put up nestboxes, work with partners to install webcams for the public to learn about the peregrines, we band the chicks and if a chick should be injured we work with others determine the best outcome for the bird. If the birds don't need our assistance, then we leave them alone. If we know the risk to the birds at a location is high, we try to find ways to stop them from nesting there and barring that find ways to improve their odds of survival. Some locations are considerably more proactive on that front than we are - Alberta for example. If a bird is injured then we advise on the best course of action for the bird.
Manitoba Conservation's job is to manage the province's natural resources for the species welfare/future on behalf of Manitobans. That means managing hunting, trapping, problem wildlife, research and monitoring (for both at-risk and not at-risk species), habitat work, public education programming, etc. Assessing research proposals is part of their mandate to manage a species and they make their decisions on the value of the results of the research to the species' management and the impact on the individuals involved. If deemed a worthwhile avenue of research with an acceptable level of impact/interaction, then it can be approved. Banding birds - songbirds, waterfowl, species-at-risk, etc - is one example of an approved research/monitoring activity that provides information on species' population dynamics, distribution, movements and behaviours.
So pop-quiz ...
1. Are the webcams everyone is enjoying interference or interaction? Are they a necessity? Are they just desirable?
2. Are public banding events interference or interaction?
3. Are fledgewatches interference or interaction? Are they a necessity? Are they just desirable?