Collector or dealer?

I have been contacted about the status of Dr Arnold-Peter Weiss who is associated with coins that will be returning to Greece.

The ANS describes him as follows:

A collector of ancient coins, Dr. Weiss is one of the founding Partners of the second incarnation of the firm Nomos AG, of Zürich, Switzerland.

In other words he is both collector and dealer.

The recent case suggested that he was actively dealing:

Weiss was aiming to sell one of them [sc. coins] for about $350,000 and two others for about $1.2 million apiece, prosecutors said.

Coin World described him as a collector:

Dr. Arnold-Peter C. Weiss, the collector who was arrested and had coins seized Jan. 3 in New York City

We can only presume that the "collection" was known as "Cabinet W". And it appears that Weiss was the intending "seller" of these coins.

And Weiss also has clear links with Nomos AG of Zurich, Switzerland. (And see also here for the link between Nomos AG, Classical Numismatic Group and Cabinet W.)

Weiss claims to be "Trustee of the American Numismatic Society (New York)" though he is not listed in that capacity on the ANS website.

For the interchange between collector and dealer see the case of the Minneapolis krater.

So do dealers collect? Do collectors deal? How long do the "valued" objects remain in a collection before another "collector" is offered the opportunity to acquire them?