£100000 isn't enough for imminent activities required to bring the case to a successful conclusion. As you say it is more of a holding situation. The sceptic in me says it is a lot easier for any government to give a small amount of budget to a case than archive a case with the negative publicity that would entail.
Scotland Yard and the Policia Judiciaria have been actively working on Madeleine's case since 2011 ... we know when SY began their review, less certain is exactly when the PJ started on theirs.
We haven't a clue where they are at operationally.
We only know from a Scotland Yard spokesperson that it is hoped that Madeleine may still be alive and that there are active leads still being followed.
I think the negative publicity would arise should the government be found to have acquiesced in throwing good money after bad, however piddling we might consider that amount, in pursuit of a case in which all avenues had been exhausted.
People are adult enough to understand that not all missing child investigations have a happy ending. When the police say they have taken it as far as they can that has to be respected.
The other side of the coin must be respected too when they say there is further to go ... and I believe that is where SY and the government are at the moment.
It should also be remembered that the Portuguese government is also paying wages for this investigation and have given no indication to date of an inclination to stop doing so.
The adverse publicity to which you refer and indeed further abrogation of Madeleine McCann's human rights would certainly arise should it be discovered that the government had reneged on following through on active lines of enquiry in her case.
