You seem to dismiss that Pando is uniquely special. The claim is that Pando is the oldest organism on Earth. Do you disagree? If so, what are some organisms that might be older?
I'm not dismissing that Pando is old or interesting. I'm saying that clonal reproduction is not especially uncommon in the plant kingdom and that we typically don't consider the resulting plants part of the same collective organism.
The same type of vegetative reproduction is happening every time a potato or garlic clove is planted, for example. Asparagus is an even closer analogy to Pando.
This is true of corals, and they are often considered "colonial" organisms instead of an individual.
That said, I don't think anyone who studies biology is particularly concerned with hard-line definitions, as nature tends to eschew them every chance it has.
I think Pando and corals being considered "modular bodyplans/habits" is perhaps a more useful concept than individual or clone.
The same type of vegetative reproduction is happening every time a potato or garlic clove is planted, for example. Asparagus is an even closer analogy to Pando.