If you're not on the Jets, you still need development IMO.
The official name is "Conditioning Camp", and attendance is actually regulated in the CBA:
(b)
Participation in Conditioning Camps will be limited to the following:
(i) Unsigned Draft Choices;
(ii) Any Player in the Entry Level System with less than 120 NHL Games
played (but who did not play in excess of 70 NHL Games in the preceding
Regular Season);
(iii) Draft-related Unrestricted Free Agents;
(iv) Players who were eligible for selection in the preceding Entry Draft but
were undrafted; and
(v) Any Player who is not in the Entry Level System, who finished the
preceding season disabled, and who submits a written request to the Club,
with a copy to the NHL and the NHLPA, to participate in his Club's
Conditioning Camp.
(c)
Ice-time during Conditioning Camp will be limited to no more than three (3)
hours per day, per Player.
(d)
No Player shall be required to participate in more than three (3) Conditioning
Camps in total for any one (1) Club (but may opt to do so in his sole discretion).
Lemieux has been at three Jets dev camps, so he won't be there unless he specifically wants to.
Lipon can't be there.