Hopefully they're that generous, but I'm concerned they'll play dirty tricks with awarding grants, considering their reputation.
For instance, they could at first grant you a small amount of money with almost no conditions except what you propose. However when you need another grant, they might say, "We're sorry, but we cannot accept your proposal and award your grant; unless you change a few things in it, then we'll award it". Eventually they'll force more control over your research to a point where they practically manipulate it to their interests. If you refuse, it's simple, your research stops due to insufficient funds. This is why having them fund your research with isn't good news long term. They'll hold power over you when it comes to continued funding. If this is a one-time grant, that won't be a problem, but if it's ongoing research and requires constant funding, this problem may arise eventually.
This of course, would be an non-issue if their were a larger market of people/organisations readily awarding grants. Because if one tries to play dirty, you simply find someone else to fund you.
Grants don't work like that thankfully. There is an application process, you write up your proposal, send it in, a committee reviews it, denies it or accepts it, and if it's accepted you get funded and have to allocate the money as you said you would within the grant proposal. Your grant history often plays a role in what grants you are eligible to receive in future. For instance, if a committee reviews your grant but feels you have too many grants at the current time (i.e., "too much money") they will be more inclined to reject it. If you are a well-known researcher and have applied for grants before through a given organization-- or, hell, sometimes just if you're a well-known researcher!-- usually there is a better chance of receiving further grants.
But the committee either accepts or rejects a grant as is. It isn't the same thing as a publication where a reviewer or editor can come back to you and say "I will give my approval if you alter this, this, and this."
It's pretty straightforward and there's not much wiggle room for dishonesty or manipulation on either party's part.