If you're linking to the other profile, I'm assuming you're also a descendant of the other profile. If the current PM is nowhere to be seen, you may consider taking over the profile.
In order to make the merge happen (before 30 days), you need to be on the trusted list. Request to be on the trusted list and if the current PM doesn't respond, file a UPMR (unresponsive profile manager report).
When I see a merge that needs to be done in my own tree and the profile manager hasn't checked in for some years, I don't even bother with the merge request, I just file the UPMR, become the PM, and then execute the merge myself.
Timelines for a UPMR:
1. File a trusted list request. In "normal" circumstances, this is approved in a few days or a week.
2. If after a week, the PM does not reply to my trusted list request, I email them and post a message to their profile comments. In the case of a PM who hasn't checked in for a long time, I send the email and post to their profile a day after I send the trusted list request.
3. One week after sending an email and posting to their profile page, if they have not added you to the trusted list, go to the profile you want to be added to, click on the family tree and scroll to the bottom to file for an unresponsive PM.
The PM will be contacted, if they do not reply, the profile will be orphaned (usually in a week or two) and you'll be sent an email that the profile is now up for adoption. Adopt it and complete the merge.
For PMs who are "active," the length of time given them to respond to a trusted list request is longer, maybe a month.
If after two weeks, your UPMR is not replied to, file again and annotate that it is a second request and indicate the date that you filed the first request.
Disclaimer: I'm not advocating for replacing yourself as PM for someone who is on vacation but for someone who did a GEDCOM dump in 2014 and hasn't been back since, I just send the trusted list request and go to the UPMR after a week. If they haven't been around for a year or two, I doubt if their feelings will be hurt if they don't manage a profile they probably have forgotten all about.