Most scientists agree that such unsourced assertions are poppycock.
It is not a proven theory, but it is not disproven. Suggesting otherwise is silly.
Some of the early supporting evidence (and most spectacularly hyped claims) from work of Moore and Moore (1984 & 1988) dealing with fossil and shell deposits on Lanai has been adequately explained by uplift over the Hawaii hot spot. But nothing has been disproved.
The mathematical models vary widely about the energy in the collapse of volcanic islands, but the velocity estimates of 40 m/s (Ritter Island model) to 100 m/s (La Palma model) and the huge volumes involved clearly support the propositions that tsunamis (some huge) have occurred and will occur again from such events. Even 1,000 meter tall ones are possible at the outside edge of the models. Think 100 Mount St. Helens occuring at once and most of the volcano, with overall height from it's base greater than Mt Everest, is underwater.
Do you have the slightest idea of the energies involved in the collapse of, say, over half of the island that we now call Oahu unleashed? It left a scar that is at least 800 feet thick and covers nearly 9,000 square miles of the ocean bottom. Yes, the energy dissipated "rapidly" and the 200 foot wave did not extend far beyond the other Hawaiian islands, but it is estimated to have still been 65 feet high when it hit ancient California some 4 1/2 hours later.
The Christmas 2005 tsunami was 10 meters, or 30 feet, max, and it was considerably closer to the event, but earthquake generated tsunami's are limited by the maximum vertical displacement of the earthquake. It's this displacement and it's resultant kinetic energy that is important, not the underlying energy in the earthquake itself. A volcanic island collapse will have several orders of magnitude more inherent and kinetic energy involved than any earthquake ever envisioned.
Check out some university web sites, such as the College of Engineering, Department of Ocean Engineering at the University of Rhode Island, or the presentations at the NSF workshop, Hawaii 30th-31st May, 2003. Look at stuff by Stéphan Grilli, the work of Keating and McGuire, or Day and Ward. There is material that argues both sides, but it is REAL material, not bald assertions without any evidence to back it up.
So please stop making unsourced claims in a scientific debate like "most scientists agree," when they clearly don't.
I'm not a geologist, geophysicist, hydrologist or forensic scientist, nor do I play one on TV. I'm betting there probably are some such experts of each (or related scientific fields) available to us here on FR, but I'll bet pretty heavy that you aren't one.
My goodness! By definition we're on the internet. Can't you even hit Google and do a simple search before posting something? The questions are interesting. Trying to stifle the debate by dismissing things you don't understand as "hogwash" is really, really, boring.