How would you value this property as an investor?

As an investor, who will not be using the property at any time or does not need to park cash, it will be silly to look at Manhattan condos as has been the case for ages.

As recently as 2 years ago there were plenty of investors buying Manhattan condo units to rent out. In fact it was something like 40% of the market for new construction.

I'm pretty sure there was a discussion here where I said buying condos to rent out didn't make sense economically and you argued that it did, which was less than 2 years ago.

Mostly parking cash for renovated condos if they had no intention of living there. The investors are still there.

Parking cash is why the cash purchases of condos are/were almost 50 percent of total condo purchases.

https://www.millersamuel.com/charts/manhattan-apartment-cash-sales-weighted-market-share-by-type/

I remember buy vs rent discussions for people who want to live in the apartment in the affordable segment of 1100-1600 per sq ft in prime areas but not condo as passive rental yield investment.

If that's the case (and I don't think it is to a large extent. That did happen but no where near the majority) then the new-ish LLC disclosure on RE purchases is certainly going to put a dent in those deals.

https://www.6sqft.com/buyers-of-all-cash-llc-purchases-above-300k-in-nyc-must-be-disclosed-under-updated-rule/

It will for dirty money but a lot of cash buyers have/had clean money. Miller Samuel chart still shows a high percentage of cash buyers and LLC disclosure rule is more than a year old if not more.

But it went from $3,000,000 to $300,000

I do see that in the link you posted but I remember filling out all the right disclosures for fincen/ anti money laundering mid year for less than $3mm purchases.