Well I'm no scientist, so let me ask you...
Would it be fair to say that such assumptions are not scientific?
And would it be fair to say that, in the absence of evidence or observation, claims of specific loose ends being tied up are also not scientific?
Would you say that an unqualified claim that evolutionary speciation arises from random mutagenic causes is unscientific?
Would it be fair to say that such assumptions are not scientific?
Only if it is fair to say that ptolomaic astronomy is not scientific. It served our purposes when we hadn't known as much or thought as deeply as we do now.
And would it be fair to say that, in the absence of evidence or observation, claims of specific loose ends being tied up are also not scientific?
Depends on what you mean by "tied up". If you mean "proven for all time", then no. If you mean a pretty satisfying explanation of some specific sub-phenomenon that needs accounting for, than, frequently, yes.
Would you say that an unqualified claim that evolutionary speciation arises from random mutagenic causes is unscientific?
op. cit.--no. But you'd have to range pretty far afield to convince me a thesis offered in seriousness--and without obvious cause for denial, and which I can see a way clear to perform experiments or field work to verify--isn't science. Some people, including some scientists I respect, are quite a bit more intolerant than I on this matter. For example, I am not bugged by the ID crowd's apparent inability to suggest a deductive experiment I can perform today, within the world's available scientific budget.
Here is the thread you were asking after.
http://www.freerepublic.com/forum/a3a8ef634710e.htm#99
I believe there is more detail about the DNA mutational clock's derivation forward-referenced from here in this thread, but this is the place to start.