> I'd like to ask a question in response ... why shouldn't they throw money at such candidate
Because they don't see that candidate. Your indication that your email was sufficient implies a few underlying assumptions which may or may not be true: a) They have enough staff to actively monitor this mailbox for submissions, b) there aren't too many useless submissions that make it unlikely the staff will be able to find the useful ones, c) that even if the staff exists, it doesn't require some bureaucratic hurdle to be met so it can be allocated to this use, d) that the staff assigned to monitoring this source is capable of assessing your accomplishments and how they relate to the grant in question.
Since there is a grant process, I think it's likely that whatever resources they do have are allocated towards assessing entries that come in through that process. There's probably more than enough work to be done in that department, such that monitoring mailboxes for the odd useful non-conformant applicant is not a priority. Even so, I assume if the stars aligned and someone happened to see the email, and knew the applicant was uniquely qualified or had time to research the person, then it's likely it might be followed up on (depending on how much interest that person had in this particular grant or field).
The important thing to consider in this is that none of these scenarios have anything to do with how qualified the applicant is. Taking issue with them not persuing you in this process when I think it's likely your application may have never even seen human eyes seems an odd response to me. The little information I have to go on makes it sound like you did the equivalent of applying for an engineering position at Apple by walking into the nearest Apple store and dropping off your resume. I'd expect about the same level of success with that. Sure, the store manager might pass it on, or know someone who is interested, but really, that's not their job or responsibility.