OP should be reimbursed for all meals during the delay as well as lodging for the night at the AMS Sheraton.

It sounds to me like the TA was able to contact the DL global ticketing folks faster than a DM agent would have been able to reach them in these circumstances, especially at the start of a holiday weekend and a time when DL has been cancelling a bunch of flights.

BTW, I'm glad to hear that the OP spent the night at the AMS Sheraton rather than struggling to/from some off-airport hotel that might have been cheaper. When you're stuck and frustrated, you might as well be comfortable and have easy access to decent F&B without going out to forage.