I don't think in my entire life I ever ate meat at a 9 days siyum, nor do I plan on doing so this year although it appears I'll probably finish a Masecheta that I learned beiyun over a long period, however there are two sides to everything. Perhaps the reason eating a 9 days siyum appears like a 'trick' to us is because we aren't appreciating the simcha of a Siyum enough. Imagine if somebody won $100m? Everybody in his vicinity would automatically smile and share in the euphoria. He would have an urge to share the happiness with his family & friends, who would naturally feel happy for him. Look how governments around the world acknowledged the necessity of family members to participate in wedding's and Brissim. אעלה את ירושלים על ראש שמחתי means that one cannot celebrate fully without Yerushalyim just as it's impossible to celebrate fully without one's family.
טוב לי תורת פיך מאלפי זהב וכסף, if we would appreciate the value of a single Halacha, Chakira, or question as worth far more than $100m, even the most perfunctory, superficial siyum would appear to be valuable enough to merit boundless celebration.
Source for shabbos leftovers?
בשערי תשובה תקנא,יא הביא בשם הברכי יוסף שיש מקילים לאכול בשר מבושל שנשתייר משבת, וכתב שבמדינתנו לא שמענו מי שמקל בזה והמיקל בכלל פורץ גדר, ור' עוד בבני יששכר (חודש תמוז אב מאמר א' אות י') שכתב שאם לא יהיה רשאי לאכול השיריים אחרי שבת יתקלקלו השיריים וימנע ולא יקנה לשבת רק בדוחק וצמצום ויהיה מניעה מעונג שבת), אך הסיק שכתב זה להלכה ולא למעשה וכך המנהג.
(I was bringing it to prove the concept, not to say you're allowed to eat)
Do you think siyum erev pesach is at all comparable to the 9 days?
Explain to me why you think they're different? If anything, the chiyuv to fast on Erev Pesach is a Mishna and not eating meat on the 9 days is a big machlokes in the first place. Either way, both definitely require participation in the siyum to some extent or another, and apparently Zoom is plausibly sufficient to reach that threshold.