Yes you have a point, Egypt has not really been militarily involved in Libya like you would have expected since they are the biggest power in the region and that borders Libya. However, i might disagree with your point that Egypt/Sissi will remain passive or limit their involvement even if Turkey openly intervenes and help GNA and MB affiliated groups regain much control of Libya. Sisi will not allow that or remain passive if that happens, whether he likes it or not he will have to intervene for his own interests and to prevent MB influence to expand in his neighbourhood from where they can provide support/space for MB groups in Egypt thereby threatening his own grip on power. You should know that Governments(even passive, corrupt, inefficient ones) will always wake up more when they see something propping up which they feel can threatened their authority, grip on power and which can embolden/help their opposition. They will not allowed that to grow and they will take measures to limit that tot he best of their ability( when a tiger sees that hes been cornered he has no choice but to fight back. lol ). Sissi is a military man and the fact that he has so far stayed clear of the ongoing war in libya( Egypt's role/involvement has been limited so far) so far doesn't means that it will remain the same if the dynamics/players involvement there changes radically. He want Turkey/Qatar backed MB groups to expand their influence in Libya, i believe he has been passive so far because that hasn't happen yet and Hafter still has more control of Libya than GNA government in Tripoli. So no real pressure for Egypt to worry as of yet. However if things change or reverse then Egypt's passivity might actually change.
Funny enough Turkey's Erdogan acted the same passive way Sissi did at the beginning of the civil war in Libya, it wasn't until they felt the threat to their own country that he finally woke up and decided to finally intervene directly, even though unfortunately by then it was abit too late, since other players had already cemented their position in the country and shaped/built up their own proxies/connections/links in the country
Morale of the story: ''Always be proactive in your neighbourhood, not reactive, else you will lose the initiative to others''. When that happens you will have only yourself to blame.
Let's see how Sissi will react when Turkey intervenes( if they really do ).
