To be fair, Bendsneyder only started to get some sense of pace as soon as the decision to let him go was made (because him not being retained is news from a while ago). It's too bad he got a more than excellent result now, but he really did have plenty of chances to show this before and he really can't put everything on 'the other tracks didn't suit the NTS'.
Besides, it's not like NTS has a huge pool to fish from, everyone who's been fighting for podium positions will either want to stay in Moto3 or get a chance at anything better in Moto2. Baltus has shown 'some' things in Red Bull Rookies last year, but pretty much everyone who performs better there is out of their league. I really can't see the likes of Holgado, Muñoz or Muñoz, Salvador or for example top riders Guevara or Artigas make a move to NTS of all places.
Basically: NTS has to gamble in terms of which riders are possible for them, and with Baltus, they do have someone who has shown excellent things in the one or two years before his full-time GP debut and who very much has the age where significant growth is possible. Not saying he will go for wins at all, but given the very limited group of riders they can choose from, Baltus is not a bad choice. I don't think he'll perform much worse than Bendsneyder did (until the pressure was off due to him being let go) and am quite certain he'll do way better than Biesiekierski.