I would suggest that since the TLD is valid and resolves, with DNSSEC, all the way from the root:
root@ent01:/etc/bind# dig +trace bnl.
; <<>> DiG 9.9.5-3ubuntu0.4-Ubuntu <<>> +trace bnl.
;; global options: +cmd
. 478397 IN NS a.root-servers.net.
. 478397 IN NS m.root-servers.net.
. 478397 IN NS g.root-servers.net.
. 478397 IN NS c.root-servers.net.
. 478397 IN NS b.root-servers.net.
. 478397 IN NS l.root-servers.net.
. 478397 IN NS f.root-servers.net.
. 478397 IN NS j.root-servers.net.
. 478397 IN NS k.root-servers.net.
. 478397 IN NS h.root-servers.net.
. 478397 IN NS e.root-servers.net.
. 478397 IN NS i.root-servers.net.
. 478397 IN NS d.root-servers.net.
;; Received 239 bytes from 208.67.222.222#53(208.67.222.222) in 303 ms
bnl. 172800 IN NS c0.nic.bnl.
bnl. 172800 IN NS b0.nic.bnl.
bnl. 172800 IN NS a2.nic.bnl.
bnl. 172800 IN NS a0.nic.bnl.
bnl. 86400 IN DS 49953 7 2 C183F9CD6ECD80BF9CB0AFF9D8F3C21DC7D14D866967C51924D0F674 9A52B5BB
bnl. 86400 IN DS 49953 7 1 1A4FAA58FB885D0290D573ADDEABCAC75A547255
bnl. 86400 IN RRSIG DS 8 1 86400 20150817170000 20150807160000 1518 . E7tbHUR9+Te+laSwBmPxDjPzdd+yoc+xtCB4cN2mG7maTXMAitkSrp9x 6kiwPknriSbE9JwvyCBTmUkR+BliHWC3BezBKbTQIpeyqWHeFjzaQ5ou z3br+hg1OTNuIwZTutDC++7+tMRRwSDM2NTUJo+GcZKMaNNCpYhd7/Vr Xzg=
;; Received 523 bytes from 192.112.36.4#53(g.root-servers.net) in 684 ms
bnl. 3600 IN A 127.0.53.53
bnl. 3600 IN RRSIG A 7 1 3600 20150826073521 20150805063521 37410 bnl. CIf4p35OC136zABgXEZ/UvnLRZQw+vLSSeRiCJ2jbKxC3wMRzDj1x0Ym npii+AvJijMFlqm5I8VRNmcAq5cyDUY98twM/4bb6eKc/qtaszLjNnw9 WV8z3TibF0bZaqugNIpmh5PIM5P5yRSq0ToyxVLmKABuiSyn7RBseWbq lA8=
bnl. 86400 IN NS b0.nic.bnl.
bnl. 86400 IN NS c0.nic.bnl.
bnl. 86400 IN NS a0.nic.bnl.
bnl. 86400 IN NS a2.nic.bnl.
bnl. 86400 IN RRSIG NS 7 1 86400 20150826073521 20150805063521 37410 bnl. SxOOfC2B4opb+Or9t+0GZCMF6ajA/uyFEXZNcXuLO9m4rREOT8K7n6l6 05CuwtFDD6LjK3vC9tbm9piXNJ0bh2qoeXjWRTCuGxeU+o7iyazA1Lx/ 1Ik7z/guZzRistMlRpkQKhF72G83jBf2Udm+biWq3jIFhnzD+Ntj4Z03 jKc=
;; Received 622 bytes from 65.22.65.1#53(b0.nic.bnl) in 52 ms
That it's "working as intended". Unless you know someone on the inside at Banca Nazionale del Lavoro, who owns the TLD, that says otherwise. It does, however, appear to be a fairly new zone, so they may simply have not completed a roll-out or are using it as a placeholder.