I'd agree with that. I think as a third choice keeper getting their personality/mentality right is important. You probably don't want anyone as a third keeper who is too ambitious, competitive and who is looking to play regularly. If they were like that it could lead to divisions in the group, the keepers after all are very much like their own little team within a team if you know what I mean.
You want someone who is supportive, a good team player who helps the other keepers along, but who could step up and do a job if an injury crisis hits.
In addition from bits and pieces I've seen and from comments made about him from other club staff from his first and second spells here he seems to have a bit of personality about him. He seems popular in the dressing room so will probably be decent for morale. So long as he's not on too high a wage I don't see it as an issue.
I can understand the viewpoints above about using a young keeper as third choice but generally keepers are better a little older having got some experience. You want your young promising keepers out getting first team experience at a slightly lower level. Then coming back to challenge for a place in the first team squad. They won't get that vital experience sat in the stands and playing youth footy. Equally if you did get an injury crisis chucking a very young keeper in could break them if they don't have sufficient first team experience at a decent level to fall back on. Counter argument is it could make them, but far more get broken in that situation than become a young keeping superstar.